question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Researchers often use two measures that have very similar items and argue that they measure different things (e.g., "I always worry when I am around cars"; "I am fearful of cars"). Lets call the hypothetical measures the Fear of Cars Measure and Anxiety from Automobiles Scale. I am interested in testing empirically ... | g16094 | [
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<p>I am assuming the following model:</p>
<p>$Y = \beta X + \epsilon$</p>
<p>Here both $X$ and $Y$ are matrices. I fit the least squares model without any regularization and get the matrix $\beta$. I would like to do the following now. I want to pick some subset $S$ of rows of $\beta$ using forward stepwise selection... | g38791 | [
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<p>I have 300 files, each file has a time series data with a class label(0 or1) for each data point.I want to build a classifier, which can predict the class of a new time series data. </p>
<ol>
<li>How should I build my training and testing data set and what model I might use. Should I combine all the files and then ... | g60147 | [
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<p>My question is how do we check the constant variance assumption in a <strong>regression model</strong>?</p> | g60148 | [
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<p>In one of my computations (result of GLM with some model values replaced with observations) I resulted with a distribution that is a lognormal distribution <strong>plus</strong> some constant. Can I still speak of lognormal distribution?</p>
<p>Again, this question is more about the statistical language and convent... | g60149 | [
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<p>I was using the <code>predxcon</code> command to graph the predicted probabilities for logistic regression. Basically I want to see the pattern for predicted probabilities of the outcome by each age group. Using <code>predxcon</code> command, it provided the graph, as well as corresponding values. </p>
<p>However, ... | g16098 | [
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<p>I work for a commercial printing company, and am collecting data regarding the quality of our printing over time (density and dot gains). Essentially, for every job I have a date, a density, and a dot gain. I would like to be able to analyze a date range and check to see if our quality seems to be getting consiste... | g60150 | [
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<p>So I want to find the long run probability of getting two heads in a row when flipping a fair coin many times. I know this answer should be 1/6 (expected number of flips to get 2H in a row is 6) but I'm trying to figure out how to use a Markov chain to solve this.</p>
<p>I think my transition matrix should be (3x3)... | g37738 | [
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<p>You draw cards from a standard 52-card deck without replacement until you get a <strong>queen of spades</strong> and stop. The cards have the values $2,3,4,\ldots,11(J),12(Q),13(K),14(A)$.</p>
<p>The first card you draw you give it to your friend and from then on, whenever you draw a card with value smaller than t... | g16106 | [
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<p>This is in the context of marking an undergraduate sociology essay in which the student has not found the predicted significant interaction effect in a Two-Way ANOVA.</p>
<p>The diagram below is schematic and doesn't depict the actual data. Imagine that the interaction effect is non-significant. The student has sai... | g60151 | [
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<p>How do I interpret a proportion in a regression model where the proportion is an independent variable (B1)? For instance, let's say B1 is 77 (or .77): how would one interpret that?</p> | g60152 | [
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<p>What would be the mathematical relation between 2 comparing survival medians (difference or relation of medians) and the HR? </p>
<p>I know that the relation of medians of survival time (MSTc/MSTi), were "i" is intervention and "c", control, is not equal to HR(i/c), although there is a correlation between these two... | g60153 | [
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<p>Let $f,g$ be two pdfs, and suppose $X$ is a random variable that has pdf $f$. Is it necessarily true that $E[f(X)] \ge E[g(X)]$?</p>
<p>Although I doubt this will help, but I got this problem from studying the <a href="http://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence" rel="nofollow">Kullback-Leibler... | g60154 | [
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<p>I collect very large samples (>1,000,000) of categorical data each day and want to see the data looks "significantly" different between days to detect errors in data collection.</p>
<p>I thought using a good-of-fit test (in particular, a G-test) would be a good fit (pun intended) for this. The expected distribution... | g15592 | [
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<p>If we have P(A|B)=P(B|A), then what is this special case called and are there special properties? I'm interested in a simpler way of computing one of them and would like to take advantage of such properties.</p> | g60155 | [
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<p>I am using a Spearman correlation for my dataset. I have three conditions and I want to know whether there is a correlation per condition. To do this I filter e.g. condition 1 and correlate variable X and variable Y. After I do the same for condition 2 and condition 3.</p>
<p>Do I have to correct for the p-values? ... | g4168 | [
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<p>As we know, <a href="http://en.wikipedia.org/wiki/Cholesky_decomposition" rel="nofollow">Cholesky decomposition</a> of $A = L*L^T$. </p>
<p>I tried to write a simple function to decompose the lower triangular matrix $L$. I know there is a C++ function of <code>GSL/gsl_linalg_cholesky_ decomp</code> that can do it. ... | g16112 | [
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<p>I have a collection of benchmarks that we run against different implementations of a system. Is there a generally-accepted way to make comparisons between multiple sets of benchmark data? Today, we take the data for system $a$ (with data points $a_1, a_2, a_3,...$) and the data for system $b$ (with data points $b_... | g19093 | [
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<p>I have to perform a mapping of a DVB-T field (the TV signal), per every location I consider the median in
time of the measurements, there are some issues, e.g. the variance seems to be proportional
to the intensity of the field because of the measuring instrumentation.</p>
<p>My first idea was to use kriging. </p... | g60156 | [
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<p>I was wondering if I could get some opinions on an issue. I'm analyzing my data using mixed-effects modeling in R (lme4 package). My model has by-subject and by-item intercepts and slopes, and random correlation parameters between them. Since the current version of lmer() does not have MCMC sampling implemented, I c... | g16114 | [
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<p>Suppose you have to choose between actions $A_1,\dots,A_n$. You have a probability distribution over each $U(A_i)$, i.e. over the utility of choosing each action. So you should choose the $A_i$ that maximizes $\mathbf E[U(A_i)]$.</p>
<p>But now you are given the opportunity to reduce your uncertainty about one of t... | g60157 | [
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<p>For example, I have two date sets from city A and B. I constructed two crosstabs and perform two chi square tests for both cities respectively, about if they have significant associations between gender and their participation in recreation activities (eg. cycling, camping). </p>
<p>The results shows there are sign... | g60158 | [
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<p><a href="http://mathoverflow.net/q/168495">I asked this question on MathOverflow a couple of days ago</a>.</p>
<p>What is the sign ($\pm$) of the third order central moment of a positive linear combination of log-normal random variables?</p>
<p>It seems to be a common notion that the skewness of random variables w... | g60159 | [
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<p>I conducted an experiment in which participants listened to sentences while looking at pictures about the sentences on a computer screen. Whether at a given time point a participant looked at the left half of a picture or the right half of a picture was recorded via an eye-tracker. </p>
<p>The study had a 2 by 2 wi... | g16115 | [
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<p>This question is related to <a href="http://stats.stackexchange.com/questions/64293/understanding-metropolis-hastings-with-asymmetric-proposal-distribution">Understanding Metropolis-Hastings with asymmetric proposal distribution</a>.</p>
<p>I'm trying to draw sample paths from a 2-state markov chain using M-H. Unfo... | g16116 | [
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<p>I have to compare two groups with data that are not normally distributed and have unequal variances. Which nonparametric test is to be used when variances are different?</p> | g49583 | [
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<p>When talking about longitudinal data, we may refer to data collected over time from the same subject / study unit repeatedly, thus there are correlations for the observations within the same subject, i.e., within-subject similarity.</p>
<p>When talking about time-series data, we also refer to the data collected ove... | g49486 | [
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<p>If $r = \frac{S_{X, Y}}{S_X S_Y}$ and $r^2 = \frac{SS_{reg}}{SS_{tot}}$, how do I prove that squaring $r$ really gets me to $r^2$ using those definitions or derivations thereof?</p>
<p>I guess the best way is to start by equating $\left[\frac{\sum{xy} - n\bar{x}\bar{y}}{\sqrt{\sum{x^2} - n\bar{x}^2}\sqrt{\sum{y^2} ... | g60160 | [
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<p>I am constructing a survey with around 10 multi-item scales. My piloting indicates that one of the most important multi-item scales (COP) has very poor reliability (.49), but there is an item in another scale (REX) which seems to hang together semantically with this COP scale. Including this item in the problem scal... | g16125 | [
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<p>Running some analysis for 65 patients who have gone through a medical treatment post-diving.
I have a dependent variable which is ordinal: 1-bad outcome, 2-okay outcome, 3-good outcome.</p>
<p>I want to test some correlations with different independent variables:</p>
<ol>
<li>Sex - nominal obviously. Should I use ... | g16126 | [
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<p>I need to classify objects using fuzzy logic. Each object is characterized by 4 features - {size, shape, color, texture}. Each feature is fuzzified by linguistic terms and some membership function. The problem is I am unable to understand how to defuzzify such that I may know which class an unknown object belongs to... | g60161 | [
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... |
<p>How to understand the homoscedasticity and heteroscedasticity in context of regression models?<br>
Is there a way to check these properties in R?</p> | g60162 | [
0.009280888363718987,
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0.03276440128684044,
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0.019884852692484856,
0.05390859395265579,
0.03438181430101395,
0.03... |
<p>How can I find a <em>Z</em> score from a p-value? I know how to look up the p-value from a <em>Z</em> score using a Normal distribution table, but I don't know how to calculate it.
For example, a question says the alpha equals 5 percent. From this, I see in my handout that the <em>Z</em> score is calculated to be 1.... | g60163 | [
0.020790791139006615,
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0.01388206984847784,
-0.031833745539188385,
-0.003616827307268977,
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0.03408906236290932,
... |
<p>In the middle of an argument that I will present to my students I'll have to prove that $E[X^2]\geq E^2[X]$, but I don't want to use Jensen's inequality to do so. Is there any elementary way to go?</p>
<p>Thanks!</p> | g15601 | [
0.00563649320974946,
0.025132428854703903,
0.021105609834194183,
-0.02845245972275734,
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0.03758428245782852,
0.025906220078468323,
0.01671527326107025,
-0.021303825080394745,
0.06... |
<p>I conduct 30 independent significance tests on $p<.05$. I observe that in $X=3$ cases the test is rejected. Can this event be caused by chance due to a multiple testing problem?</p>
<p>I understand that $X$ is binomially distributed, with expectation $E(X)=np=1.5$. What is the null hypothesis I should test, is i... | g16128 | [
0.05775075778365135,
0.028011806309223175,
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0.022927451878786087,
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... |
<p>Which is a better method of data reduction - factor analysis or principal component analysis?</p> | g60164 | [
0.07288646697998047,
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0.015385122038424015,
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0.03599941357970238,
0.04169278219342232,
0.03433343768119812,
0.01237... |
<p>What method can I use to test if there is a correlation between two sets of data? The correlation coefficient works if there is a linear association, but if I have two sets that are clearly (visually by graph) correlated in a non-linear way, how can I test that? Is there a coefficient or a special method?</p> | g16129 | [
0.02782345749437809,
0.007160448934882879,
0.038489341735839844,
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0.008915702812373638,
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0.029048653319478035,
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0.02730756625533104,
0.0138... |
<p>I need to do a grid search to optimize SVM parameters gamma, C and epsilon (svm from <a href="http://cran.r-project.org/web/packages/e1071/e1071.pdf" rel="nofollow">e1071 r package</a>). The problem is that I have a fairly large data set, about 100000 rows and 40 variables.</p>
<p>I have concluded that I can probab... | g60165 | [
0.017246391624212265,
0.050467994064092636,
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0.007706762757152319,
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0.07424692809581757,
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0.0029399802442640066,
0.021991310641169548,
0... |
<p>I have a Poisson formulation with the following parameters:</p>
<ul>
<li>I see 90 people in a city an hour</li>
<li>1.2% of people in the city are Indian</li>
</ul>
<p>How would I calculate:</p>
<ul>
<li>The maximum amount of time before I would see any Indian person with the highest probability</li>
<li>The amou... | g2957 | [
0.03092903271317482,
0.028767358511686325,
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0.05674828961491585,
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0.029206160455942154,
0.00... |
<p>I'm trying to compute a mixed model using jags (R2jags) and I got very strange divergence. The chains started so well, very well according to the results expected (also see <code>lmer</code> output of the same model below). But at certain point, the chains went crazy. Just look at the traceplot for <strong>delta_tau... | g60166 | [
-0.000012207440704514738,
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0.0016006651567295194,
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0.05514511093497276,
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0.02504733018577099,
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-0.03551999852061272,
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0.06598171591758728,
0.05041614547371864,
... |
<p>Hi I'm taking a graduate course in Statistics and we've been covering Test statistics, and other concepts. </p>
<p>However, I am often able to apply the formulas and develop a sort-of intuition on how stuff works but I am often left with a feeling that perhaps if I backed up my study with simulated experiments I wi... | g60167 | [
0.017579806968569756,
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-0.026018429547548294,
0.02164372242987156,
0.01147513184696436,
0.06224521994590759,
-0.... |
<p>Is there any comprehensive reference on (or introduction to) how people have tried to model non-independent random variables? I already know about mixing processes, which express in various ways according to various coefficients how "future" events depend on "past" events, but that's about it...</p> | g45552 | [
-0.029870809987187386,
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0.0011852444149553776,
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0.026270821690559387,
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-0.02666383795440197,
-0.009238695725798607,
0.023300781846046448,
0.03874582424759865,
... |
<p>Suppose we have a simple linear regression model $Z = aX + bY$ and would like to test the null hypothesis $H_0: a=b=\frac{1}{2}$ against the general alternative. </p>
<p>I think one can use the estimate of $\hat{a}$ and $SE(\hat{a})$ and further apply a $Z$-test to get the confidence interval around $\frac{1}{2}$. ... | g16135 | [
0.013434162363409996,
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0.014050880447030067,
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-0.03832327201962471,
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0.0745106041431427,
0.05002269148826599,
0.01777... |
<p>I have been reading quite a few papers and recently have started analyzing some data on a review that I am doing.</p>
<p>I am trying to examine the effect of two different treatment options on a group of patients. Using Kaplan-Meier analysis, the p-value is statistically significant at 0.03.
However I believe that... | g16136 | [
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0.0007309718639589846,
0.037815067917108536,
-0.004537070635706186,
0.07348664849996567... |
<p>What is the difference between data mining, statistics, machine learning and AI?</p>
<p>Would it be accurate to say that they are 4 fields attempting to solve very similar problems but with different approaches? What exactly do they have in common and where do they differ? If there is some kind of hierarchy between... | g49300 | [
0.07437755912542343,
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0.020261771976947784,
0.052015189081430435,
-... |
<p>I am collecting longitudinal data using for 4 time waves. Although the survey is administrated to the same population, different individuals may decide to complete it at each time point. As a result there are a number of individuals that only completed it once, others that completed it twice, some that completed it... | g60168 | [
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0.013758276589214802,
0.004509544000029564,
-0.03568567708134651,
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... |
<p>A database of (population, area, shape) can be used to map population density by assigning a constant value of population/area to each shape (which is a polygon such as a Census block, tract, county, state, whatever). Populations are usually not uniformly distributed within their polygons, however. <a href="http:/... | g16141 | [
0.008889450691640377,
0.02315119467675686,
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0.016930516809225082,
0.016283897683024406,
0.05468213930726051,
0.016110237687826157,
0.07340361922979355,
0.00... |
<p>The standard sum of squares as I know it is:
$$
\sum(X-m)^2
$$
where $m$ is the mean. I ran into a different one which can be written two ways:
$$
\sum(X^2) - \frac{(\sum X)^2}{n} = \sum(X^2) - m\sum X
$$
I believe the latter is called the "correction term for the mean" (e.g. <a href="http://www.itl.nist.gov/div898/... | g60169 | [
0.031048042699694633,
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0.03885573893785477,
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0.010331861674785614,
-0.03268113359808922,
0.06309633702039719,
0.0742812529206276,
0.01... |
<p>I'm pretty new at this and I'm picking my way through the steps for running PCA on a 2D numpy array. Each subarray represents all pixels of an image (all rows & cols flattened). Example:</p>
<pre><code>a = np.array([ [1,2,3], [4,5,6], [7,8,9] ])
# so, a[0], a[1], a[2] each represent a separate image
</code></... | g60170 | [
0.021280961111187935,
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0.004913919139653444,
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0.04060786962509155,
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0.061395175755023956,
0.03317190706729889,
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-0.021292099729180336,
0.02631472609937191,
0.0707683339715004,
0.0246651079505682,
0.024304... |
<p>During studying the convergence assessment on Markov Chain Monte Carlo, I once read the following statement:</p>
<blockquote>
<p>A slowly converging sampler may be indistinguishable from one that will never converge(e.g., due to nonidentifiability)!</p>
</blockquote>
<p>How to understand this statement? Thanks!<... | g60171 | [
0.07222417742013931,
-0.007106138858944178,
0.009943808428943157,
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0.01056545227766037,
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0.0377717986702919,
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-0.010762556456029415,
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0.05789705365896225,
0.01582803763449192,
0.042... |
<p>I have a list of categories A, B, C, etc, each with a probability:</p>
<pre><code>A .015
B .005
C .02
D ... etc.
</code></pre>
<p>I need to find if the difference between two of these categories, say</p>
<pre><code>diff(C,A) = .02 - .015 = 0.005
</code></pre>
<p>is statistically significant. I have bee... | g60172 | [
-0.004567438270896673,
0.004773000720888376,
-0.0015631548594683409,
-0.06345519423484802,
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0.05036746338009834,
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-0.04564976692199707,
-0.007758057676255703,
0.004332120064646006,
0.022802764549851418,
-... |
<p>I'm trying to understand the result I see in my graph below. Usually, I tend to use Excel and get a linear-regression line but in the case below I'm using R and I get a polynomial regression with the command:</p>
<pre><code>ggplot(visual1, aes(ISSUE_DATE,COUNTED)) + geom_point() + geom_smooth()
</code></pre>
<p>So... | g60173 | [
0.02940104715526104,
-0.014897993765771389,
-0.012697657570242882,
-0.01674409583210945,
0.02776341140270233,
0.016378674656152725,
0.04371829703450203,
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-0.07268648594617844,
0.019454341381788254,
0.10312557220458984,
0.0516338050365448,
-0.055... |
<h1>Problem #1: easy, probably solved</h1>
<p>Suppose someone holds a party (A) and invites $n_A$ people. You're not attending a party, but you get full list of guests' identity card and are told that out of $n_A$ people $m_A$ were male (obviously, $n_A-m_A$ were female).</p>
<p>After some time, there's another party... | g16151 | [
-0.014077192172408104,
0.013067874126136303,
-0.007422548718750477,
-0.012353313155472279,
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-0.03368953987956047,
-0.02277909778058529,
0.03050505369901657,
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0.03916550055146217,
-0.047207798808813095,
0.0261051245033741,
0.015251324512064457,
0.... |
<p>I want to calculate the best state sequence for a observation sequence. To do that, I want to use Viterbi algorithm.</p>
<p>In my problem, there are two properties:</p>
<ol>
<li><p>There can be only one observation possibility for a state. However the opposite is not true : an observation can be generated by more ... | g60174 | [
-0.006224004086107016,
-0.01688709668815136,
0.00833025574684143,
0.011506834998726845,
0.010820405557751656,
-0.011626655235886574,
0.02780035510659218,
0.0669681653380394,
0.010605917312204838,
0.003996012266725302,
0.0077749923802912235,
-0.007604238111525774,
0.03800003603100777,
0.014... |
<p>I am testing the co-movement between 2 exchanges by using the dynamic conditional correlation (DCC) developed by Robert Engle (2002). I want to apply this method in stata 12 and used this command: </p>
<pre><code>Mgarch DCC (var1 var2=), arch(1) garch(1) distribution(t)
</code></pre>
<p>I read that it should give ... | g16153 | [
0.036532945930957794,
0.0063252924010157585,
-0.0016920189373195171,
-0.06769508123397827,
0.06385210156440735,
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0.07286552339792252,
0.00023952870105858892,
0.0023077726364135742,
-0.046335283666849136,
-0.009856494143605232,
0.018842017278075218,
0.06534486263990402,
... |
<p>PSY's music video <a href="http://www.youtube.com/watch?v=9bZkp7q19f0">"Gangnam style"</a> is popular, after a little more than 2 months it has about 540 million viewers. I learned this from my preteen children at dinner last week and soon the discussion went in the direction of if it was possible to do some kind of... | g43443 | [
-0.0017740556504577398,
0.04721476510167122,
0.002123587066307664,
0.020515143871307373,
0.005023464560508728,
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0.05793994665145874,
0.01516506914049387,
-0.04778560996055603,
-0.025448940694332123,
0.008295677602291107,
0.005026704166084528,
0.027790311723947525,
0.02... |
<p>I want to calculate the VaR with Monte Carlo Simulation, I am referring to this page:</p>
<p><a href="http://financetrain.com/calculating-var-using-monte-carlo-simulation/" rel="nofollow">http://financetrain.com/calculating-var-using-monte-carlo-simulation/</a></p>
<p>which was created to the JP Morgan desrciption... | g16156 | [
0.03711625933647156,
0.03869657218456268,
-0.019486350938677788,
-0.0074614486657083035,
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0.014768769033253193,
0.03183795139193535,
0.023717880249023438,
0.008816414512693882,
0.017804978415369987,
-0.051531076431274414,
0.006124226376414299,
0.012520595453679562,
-0... |
<p><a href="http://www.geog.ucsb.edu/~joel/g210_w07/lecture_notes/lect01/oh07_01_2.html" rel="nofollow">This webpage</a> says: </p>
<blockquote>
<p>Inferential Statistics - Deductive Approach</p>
<p>Descriptive Statistics - Inductive Approach</p>
</blockquote>
<p>But I doubt it. If I understand correctly, </p... | g60175 | [
0.03365127369761467,
0.030501239001750946,
-0.009801100939512253,
-0.03753472864627838,
0.013922879472374916,
-0.03481923043727875,
0.03910363093018532,
0.052827510982751846,
-0.04518934339284897,
-0.051971375942230225,
0.015195868909358978,
0.013323187828063965,
0.08528221398591995,
0.004... |
<p>It seems that it is possible to get similar results to a neural network with a multivariate linear regression in some cases, and multivariate linear regression is super fast and easy.</p>
<p>Under what circumstances can neural networks give better results than multivariate linear regression?</p> | g60176 | [
0.062469348311424255,
-0.018976222723722458,
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0.04597930982708931,
0.011971425265073776,
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0.01189435739070177,
0.015753749758005142,
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-0.0167485810816288,
0.013654274865984917,
-0.004290523938834667,
0.011755429208278656,
0.02... |
<p>It appears that the binomial distribution is very similar in form to the beta distribution and that I can re-parametrize constants on either pdf to make them look the same. So, why do we need the beta distribution? Is it for a specific purpose? Thanks!</p> | g60177 | [
0.04113119840621948,
-0.03203071281313896,
0.00845731794834137,
-0.015808526426553726,
0.027227602899074554,
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0.015503337606787682,
-0.05573297664523125,
-0.05232499912381172,
0.005721081979572773,
-0.00825568474829197,
0.03219553455710411,
-0.02... |
<p>In my field, it is common to rotate levels of an experimental condition across different presentation lists in a within-subjects design. This is done to prevent a particular participant from seeing every level of every experimental item, while at the same time, allowing them to still see equal instances of each type... | g16160 | [
-0.02865169756114483,
-0.01619919389486313,
-0.011189978569746017,
-0.04448901116847992,
-0.005714136641472578,
0.019395703449845314,
0.03855833038687706,
-0.019773071631789207,
-0.022759709507226944,
-0.007027474232017994,
0.011359439231455326,
-0.02828873321413994,
0.020750081166625023,
... |
<p>In wikipedia the definition of a parametric model is the following:</p>
<blockquote>
<p>A parametric model is a collection of distributions, each of which is indexed by a unique finite-dimensional parameter: $\mathcal{P}=\{\mathbb{P}_{\theta} : \theta \in \Theta\}$, where $\theta$ is a parameter and $\Theta \subs... | g60178 | [
0.02628989703953266,
0.04866612330079079,
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0.027521051466464996,
0.015240288339555264,
0.025702472776174545,
0.0001747191563481465,
-0.04008572921156883,
-0.013641688972711563,
-0.10397680848836899,
0.02328253723680973,
0.00741045456379652,
0.01... |
<p>I want to obtain a correlation between the accuracy of two linguistic features by language learners. The learners wrote a number of essays, and the number of correct and incorrect use of the article and the plural marker was tallied in each essay. The data for a learner look like the following, though the number of ... | g60179 | [
-0.006868254393339157,
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0.033847127109766006,
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0.0383... |
<p>Is there any test for comparing the directions, magnitudes, etc of PCA results for different samples? I'm leaving the nature of the test deliberately vague because I'd like to hear all the various possibilities... e.g. there might be (and I'm speculating here) a test comparing the sizes of the first principal compon... | g18825 | [
-0.007620537653565407,
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0.014854555949568748,
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0.06400704383850098,
0.0037970247212797403,
0.0311047974973917,
0.025... |
<p>Apart from detecting trend from a time series plot, how do you test for its presence before removing the trend using moving average? </p>
<p>I fitted a mathematical trend to the data and the slope was approximately zero, does that mean there is no trend?</p> | g60180 | [
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0.0... |
<p>Suppose I have a leptokurtic variable that I would like to transform to normality. What transformations can accomplish this task? I am well aware that transforming data may not always be desirable, but as an academic pursuit, suppose I want to "hammer" the data into normality. Additionally, as you can tell from the... | g60181 | [
-0.024110672995448112,
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<p>Is there any relation between heat kernel and Laplacian? I know what each of them is but I am not sure about the relation between them.</p> | g60182 | [
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<p>I'm running a fixed effects model with the <code>plm</code> function, and I'm looking for help interpreting an aspect of the output. If the output reads:</p>
<pre><code>Call:
plm(formula = dependentvariable ~ independentvars, data = data, model = "within",
type="time")
Unbalanced Panel: n=176, T=1-2, N=211
R... | g60183 | [
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0.... |
<p>I have been reading about MLE as a method of generating a fitted distribution.</p>
<p>I came across a <a href="http://www.itl.nist.gov/div898/handbook/eda/section3/eda3652.htm">statement</a> saying that maximum likelihood estimates "have approximate normal distributions."</p>
<p>Does this mean that if I apply MLE ... | g60184 | [
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0.03769182041287422,
... |
<p>I am looking for an appropriate statistical method to test my hypothesis that there is no significant difference between counts conducted by 2 individuals of the same data.</p>
<p>The data is as follows:</p>
<p>I have videos of fish migrating up a river, and 2 different people counting the videos.</p>
<p>I have 9... | g60185 | [
0.06100501865148544,
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0.0763881653547287,
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0.061133287847042084,
0.003120406996458769,
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0.01... |
<p>I am trying to complete my PHD and I am using a survey to determine students' perception of their preparedness to teach and want to compare their answers to what their final summative evaluation says about their ability to teach. I created a questionnaire for the students to answer that reflects each of the areas of... | g21865 | [
-0.06350865215063095,
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0.03473276272416115,
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0.04300510510802269,
0.0057... |
<p>I'm considering a Hidden Markov Model as follows:</p>
<p>$X_{n+1} = F_n(X_n,\Theta)$</p>
<p>$Y_n = G_n(X_n,\Theta)$</p>
<p>where the $Y_n$ are the observations, the $X_n$ the hidden states and $\Theta$ the parameters. At some point, I have to deal with this probability</p>
<p>$p(X_k = x_k | X_{k-1} = x_{k-1}, Y_... | g60186 | [
-0.02702120505273342,
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0.02434474788606167,
0.05221235379576683,
0.03... |
<p>Unit of analysis: States (39)<br>
Time: 3 years<br>
Total observations: 117<br>
Dependent variable: % children graduating within 4 years from high school<br>
Independent variable: 8 composite scores ranging from 1-30. These scores did NOT change throughout the period of examination (i.e. 8 measures are time-invarian... | g60187 | [
-0.014560802839696407,
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-0.029268747195601463,
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0.011039825156331062,
-0... |
<p>$L$-estimators are based on the ordered observations $X_{(1)} \leq X_{(2)} \leq \ldots \leq X_{(n)}$ of the random sample $X_1, X_2, \ldots , X_n$. The general $L$-estimtor can be written in the form:
$$
T_n = \sum_{i=1}^{n}{c_{ni} h(X_{(i)})} + \sum_{j=1}^{k}{a_j h^{*}(X_{( [n p_{j} ] +1)})}
$$
where $0< p_1 \l... | g16168 | [
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0.04896389693021774,
0.010454083792865276,
0.... |
<p>I'm trying to decide if a component of a PCA shall be retained, or not. There are a gazillion of criteria based on the magnitude of the eigenvalue, described and compared e.g. <a href="http://labs.eeb.utoronto.ca/jackson/ecology%2074.pdf">here</a> or <a href="http://www.researchgate.net/publication/222533061_How_ma... | g60188 | [
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0.050858162343502045,
0.006539135705679655,
0.07199491560459137,
0.066... |
<p>I was under the impression that the function <code>lmer()</code> in the <code>lme4</code> package didn't produce p-values (see <a href="https://stat.ethz.ch/pipermail/r-help/2006-May/094765.html" rel="nofollow"><code>lmer</code>, p-values and all that</a>).</p>
<p>I've been using MCMC generated p values instead as ... | g60189 | [
0.011356092058122158,
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0.015197617001831532,
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0.00814488623291254,
0.07489805668592453,
0.053... |
<p>Here is the whole question:</p>
<blockquote>
<p>(a)A Simulation Study (Logistic Regression). Assume $y|x \sim \mathrm{Binary}(p)$,
where $p= \mathrm{E}(y|x)$, and $\mathrm{logit}(p_i)=-1+5.1x_{1i}-0.3*x_{2i}$. Generate data
with $x_{1i}\sim \mathrm{Unif}(0,1)$, $x_{2i}=1$ for $i$ odd and $x_{2i}=0$ for $i$ ev... | g60190 | [
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0.007051742635667324,
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0.010827377438545227,
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0.006914048455655575,
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0.00045478204265236855,
0.05053117126226425,
0.023766301572322845,
... |
<p>This question may appear to be quite odd, but the following explanation should make it a little more comprehensible. </p>
<p>I work on the analysis of population trends of birds. In our team, we work with a simple trend index, that is calculated as </p>
<p>$$\frac{\rho_t - \rho_{t+1}}{\rho_t + \rho_{t+1}} = \frac{... | g60191 | [
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0.03289847820997238,
0.007439903914928436,
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0.015497459098696709,
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0.05750494822859764,
0.06941834837198257,
0.02... |
<p>What do all the symbols mean? Thanks for your help!</p>
<pre><code>Table 2
Summary of Hierarchical Regression Analysis for Variables Predicting Depression (N=108)
Model 1 Model 2
Variable B SE B β B SE B β
RSES -.613 .119 -.449 ... | g16173 | [
0.007932865060865879,
-0.0302335973829031,
-0.022973481565713882,
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0.0500500313937664,
0.018198717385530472,
0.08537465333938599,
0.03239211440086365,
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0.08981480449438095,
-0.0021982097532600164,
-0.0067... |
<p>How do you know whether you suffer from it? </p>
<p>Let's suppose I have a 2 class problem - 2000 training examples and 30 features. While it works good for the most part, sometimes I get edge cases that are so horribly misclassified. I feel like it's because there is a lot of dimensions and too little examples.</p... | g60192 | [
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0.027771351858973503,
0.0675402283668518,
0.0489... |
<p>I am a grad student. I am struggling with core statistics courses: probability, statistical inference.</p>
<p>In probability, for example, prove unbiased estimator for uniform. In statistical inference, find the UMVUE for an estimator.</p>
<p>American stat dept has either highly qualified foreign students, or th... | g19451 | [
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0.06590630859136581,
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0.02856648527085781,
-0.00241... |
<p>I am learning Latent Semantic Analysis. After we have the SVD decomposition of term-document matrix, how to infer topics from that?</p>
<p>For example, how to get the following result:</p>
<p>Topic 1: apple, orange, fruit
Topic 2: computer, machine</p> | g60193 | [
0.02967423014342785,
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0.05529441684484482,
-0.03... |
<p>How do I show that Fisher's and Normal Linear decision rule differ by a constant? </p>
<p>Thank you for your help.</p> | g60194 | [
0.018357915803790092,
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0.011802964843809605,
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0.07105778157711029,
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0.01... |
<p>A previous <a href="https://stats.stackexchange.com/questions/12128/what-does-orthogonal-mean-in-the-context-of-statistics">question</a> received a <a href="http://www.psych.umn.edu/faculty/waller/classes/FA2010/Readings/rodgers.pdf" rel="nofollow">linked answer</a> as below:</p>
<blockquote>
<p>The first importa... | g60195 | [
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0.03428831323981285,
0.020361101254820824,
0.029906390234827995,
0.018853144720196724,
0.015595024451613426,
0.033718857914209366,
0.03936260938644409,
-0... |
<p>Suppose:</p>
<p>For each input data, I could obtain true result as well as experiment result from my algorithm, one example is</p>
<p>The true result is <code>A = {a, b, c},</code></p>
<p>Experiment result is <code>B = {b (0.3), c (0.8)}</code>, the numbers denote the probability of the element's presence.</p>
<... | g60196 | [
0.01627529226243496,
-0.022645961493253708,
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0.009823179803788662,
-0.030062297359108925,
0.03171100839972496,
0.053516194224357605,
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0.038332682102918625,
-0.03675173595547676,
0.02528095431625843,
0.01752323843538761,
0.06... |
<p>I have 3 arms in a trial. I want to compare results of a survey before during and on completion of a treatment. Data is not normally distributed. What test should I use?</p> | g291 | [
0.04845752194523811,
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0.07072030752897263,
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... |
<p>How to cross-validate a model with log-transformed x's and y's and obtain the RMSE in the original units? For example, I got an error message when I used the cvTools package:</p>
<pre><code> library(cvTools)
library("robustbase")
data("coleman")
set.seed(1234)
folds <- cvFolds(nrow(coleman), K = 5, R = 10)
... | g16177 | [
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0.01770872250199318,
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0.07475659251213074,
0.0293582733720541,
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0.0070952861569821835,
-0.017134306952357292,
0.027422577142715454,
0.06541112065315247,
-0.0... |
<p>Suppose we have the following model:</p>
<p><img src="http://i.stack.imgur.com/ogehC.png" alt="enter image description here"></p>
<p>ADF would test if $\gamma$ equals 0 (null hypothesis), and rejects it if the statistic is sufficiently negative in favor of $\gamma < 0.$ But what if, say, gamma equals -5? Wouldn... | g60197 | [
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-0.0... |
<p>I have a simple set of data indicating completion rates that I want to present as a ranked/league table. The data available is that for every visit of a person, a plan document should be completed by the specialist. These documents are not always completed, and we want to drive more completion.</p>
<p>The challen... | g16179 | [
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0.01871451921761036,
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0.0008832815801724792,
0.037715230137109756,
0.04192386567592621,
0.0013683283468708396,
0.08729869872331619,
-... |
<p>I would like to generate normal random variable vector $\boldsymbol{x}_1$, which is correlated with $\boldsymbol{x}_2$. Also, I would like to introduce some kind of spatial auto-correlation into $\boldsymbol{x}_1$, and $\boldsymbol{x}_2$, respectively. How can we do this with standard statistical software like <code... | g60198 | [
0.03800678253173828,
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0.006894534453749657,
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0.019335787743330002,
0.0002446880971547216,
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0.038859881460666656,
0.07544596493244171,
0.021837232634425163,
0.... |
<p>I have blanks in my continuous data as the title says. I'm trying to do a pretty complex regression. I don't want to really mention exactly what type as I'd rather leave that detail out for the sake of trying to get a more general strategy or approach (unless it is absolutely necessary).</p>
<p>The variables that... | g60199 | [
0.03666120395064354,
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0.006883462890982628,
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0.03664737567305565,
0.019892750307917595,
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0.040222011506557465,
0.04754427820444107,
0.018981119617819786,
-0.0... |
<p>Consider the following text</p>
<blockquote>
<p>The verdict is out, the jury has held MS guilty of infringements and
levied penalties aggregating to $1.50Bn. It will be a massive blow to
the reputation of MS. The defendants, NK, on the other hand were
elated. It was an important verdict for them to win. The... | g60200 | [
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0.035823069512844086,
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0.03698330372571945,
0.042085520923137665,
0.04188890755176544,
0.03641468286514282,
0.00... |
<p>I've found how to measure the smoothness of a time series in R from <a href="http://stats.stackexchange.com/q/24607/6981">this previous CV question</a>, and I think I understand it, but I don't have access to R, only to Excel. How would I calculate this?</p>
<p>Given this formula for a normalized version of smoothn... | g60201 | [
0.035203736275434494,
0.00582108274102211,
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0.07884842157363892,
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-0.03... |
<p>This wikipedia <a href="http://en.wikipedia.org/wiki/Heteroscedasticity#Detection">link</a> lists a number of techniques to detect OLS residuals heteroscedasticity. I would like to learn which hands-on technique is more efficient in detecting regions affected by heteroscedasticity.</p>
<p>For example, here the cent... | g60202 | [
0.05816078558564186,
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0.06845993548631668,
0.04549822583794594,
0.0... |
<p>Is there a way to use the factor scores from one dataset to "partial out" the effects from another dataset which has the same variables? Basically I have two datasets: healthy people and sick people. I'd run factor analysis on the healthy set (called "base"), restricting to only one factor so that it acts like a sum... | g44595 | [
0.05247461423277855,
-0.05421570688486099,
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0.040525175631046295,
0.03785185515880585,
0.015605393797159195,
-0.03... |
<p>I'm new to forecasting using neural networks. I have decided to use feedforward backpropagation algorithm. What are the input values if I have past data and what is the technique to select input values?</p> | g44602 | [
0.0284279752522707,
-0.030695725232362747,
0.029037928208708763,
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0.06439071148633957,
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0.02290191687643528,
0.02248510532081127,
0.0661... |
<p>In an article, I recently came across the mention of first and second order U-type statistics without further detail.</p>
<p>Does anyone know what U-type statistics are?<br>
References will be highly appreciated.</p> | g43001 | [
0.013199076056480408,
0.04691259562969208,
-0.012163527309894562,
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0.03401948884129524,
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0.0035689594224095345,
0.02384120039641857,
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<p>When I run a 2x4x5x6 (Sex*AgeGroup*HighestDegree*Ethnicity) MANOVA (with 20 dependent variables) in SPSS, it presents tests of between subjects effects for each of the IVs and their interactions after the main MANOVA stats as a kind of post hoc. I thought these tests were 2*4*5*6 factorial ANOVAs for each of the DVs... | g16181 | [
0.011594624258577824,
-0.057048797607421875,
-0.0016372432000935078,
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0.02595710940659046,
0.009846451692283154,... |
<p>I am trying to program a pathway analysis. Briefly, I have a list of genes which contain 1 or more mutations. I have mapped these genes to pathways, and I want find out if any pathways are over-represented in these mappings.</p>
<p>My approach is permutation based: I randomly place an equivalent number of mutations... | g38578 | [
0.013127217069268227,
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0.02820960059762001,
... |
<p>When we consider Queueing theory scenarios where individuals arrive to a serving node and queue up, usually a Poisson process is used to model the arrival times. These scenarios come up in network routing problems. I'd appreciate an intuitive explanation as to why a Poisson process is best suited to model the arriva... | g37573 | [
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0.0404224656522274,
-0.027197493240237236,
-0.02847682125866413,
0.011561580933630466,
-0.0... |
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