question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>Twenty possible predictor variables in data set. One outcome variable.</p>
<p>Some of the predictor variables are not linear. So a standard linear multiple regression approach probably won't do. (And I do not want to transform the variables using some arbitrary "cubic," "quadratic" approach -- leave the underlyi... | 37,691 |
<p>I have two versions of the same question:</p>
<ol>
<li>Given a list of numbers (with possible duplicates), how to find a k-subset (with possible duplicates) that maximize the variance? is there a more efficient way than the obvious "check-all-k-subsets"?</li>
<li>Given a set of numbers, how do I select from that s... | 33,225 |
<p>Within three distinct groups (three soil types), I have three categorical predictor variables (pH, ionic strength, and SAR). My response variable is continuous (% optical transmission). What statistical analysis do I need to check for interactions between the predictor variables and significant differences in the re... | 71,650 |
<blockquote>
<p>Very close to: <a href="http://stats.stackexchange.com/questions/24820/joint-gaussian-of-two-gaussians/24822#24822">Joint Gaussian of two Gaussians</a></p>
</blockquote>
<p>I am trying to find the Bayesian classifier for two classes given by the following bivariate Gaussian distributions:</p>
<p>$$p... | 71,651 |
<p>What (with justification) is a valid post-hoc for a two-way ANOVA main effect, if no interaction is present?</p>
<p>Example two-way fixed effect ANOVA:</p>
<pre><code>> aov.example <- aov(Response ~ IV1 * IV2, data=data)
> summary(aov.example)
Df Sum Sq Mean Sq F value Pr(>F)
IV1 ... | 71,652 |
<p>I've run a small experiment and need to test the data by comparing the frequencies of different treatments, specifically, whether they are significantly different. I think the chi-squared test is appropriate, but I am not sure how to execute it because it's somewhat outside the range of my course.</p>
<p>Simplifyin... | 33,227 |
<p>I am new to time series analysis and I would appreciate if anyone could provide me some insight on it.
I am trying to analyse a past series of numbers that fluctuates between 107 & 210 with a normal frequency bell curve distribution of mean 162.
What is a suitable approach to forecast short-term future range for... | 37,875 |
<p>I was wondering if there exist efficient <a href="http://en.wikipedia.org/wiki/Online_algorithm" rel="nofollow">online</a> or <a href="http://en.wikipedia.org/wiki/Dynamic_algorithm" rel="nofollow">dynamic</a> algorithm for fitting a normal distribution to data as it comes in. I am interested in two variants:</p>
<... | 33,229 |
<p>I have a data set of J raters who each give ratings to I objects (on say a scale of 1 to 5). My goal would be to construct some kind of overall rating for each i based on all of the raters' scores.</p>
<p>My first approach, which I have seen used before, is to construct a standardized score specific to each rater-o... | 71,653 |
<p>Can somebody tell me the difference between margins of error and confidence intervals? On the Internet I see these two meanings getting used interchangeably.</p>
<p>Is it right to say,</p>
<p>"Confidence intervals are shown as 1.96 and displayed on the graphs as error margins"?</p> | 33,232 |
<p>Why do we need to use a base category (normalised to zero) when working with multinomial logit models? </p>
<p>I would also like to ask why do we need to report conditional logit coefficients? </p>
<p>Wouldn't marginal effects give us a better idea of the probability of belonging to a certain class? </p> | 71,654 |
<p>I'm looking for the correct equation to compute the weighted unbiased sample covariance. Internet sources are quite rare on this theme and they all use different equations.</p>
<p>The most likely equation I've found is this one:</p>
<p>$q_{jk}=\frac{\sum_{i=1}^{N}w_i}{\left(\sum_{i=1}^{N}w_i\right)^2-\sum_{i=1}^{N... | 71,655 |
<p>I've gone through Hidden Markov models (HMM) for the past few months. However there are a few things that are confusing.</p>
<p>The set up is simple: I have to model some human gestures such as walking, jumping, and falling. The observed data have been obtained via an accelerometer while the person was doing the mo... | 33,234 |
<p>I have several datasets on the order of thousands of points. The values in each dataset are X,Y,Z referring to a coordinate in space. The Z-value represents a difference in elevation at coordinate pair (x,y).</p>
<p>Typically in my field of GIS, elevation error is referenced in RMSE by subtracting the ground-trut... | 44,154 |
<p>I'm used to doing descriptive modeling where I'm very concerned with parsimony and interpretability, but now I have a project that calls for the opposite and I'd like advice on techniques I should look into.</p>
<p>I have a tool (an R function) that essentially creates random graphs based on 11 parameters. There ar... | 71,656 |
<p>I am performing ordinal regression on several datasets, I have 5 ordered response categories and only one explanatory variable X.
For each dataset I run the analysis 3 times, each time using a different link function (1. probit, 2. logit, 3. comploglog) and I calculate the AIC to see which function fits my data best... | 49,590 |
<p>I have to do an empirical analysis for a statistics paper. For this I want to show the differences of dependence structure for a specific data set.</p>
<p>So I selected 2 stock prices, transformed them into the returns and started to measure the dependency with R. So far it is no problem, I have a result for Bravai... | 33,238 |
<p>I am trying to optimize <a href="http://scikit-learn.org/stable/modules/generated/sklearn.linear_model.SGDRegressor.html" rel="nofollow">sklearn.linear_model.SGDRegressor</a>, and I was wondering if people could point me in which direction I should try to optimize? Personal experience and literature are both welcome... | 71,657 |
<p>How to check if those values are "dependent" ? Take a look on the values in second column coz the difference between them is really huge so it's hard to choose the scale. Any propositions of checking "dependence" between them are welcome. I was thinking about correlation but I am new in statistic so please let me kn... | 71,658 |
<p>I feel like I'm missing something obvious, but here we go. I have auto-correlated data measured in triplicate for two (or more) treatments. Something like this:</p>
<pre><code>t <- 3:20 #times in my real dataset are possibly not always equidistant
a <- structure(c(0.652492388457625, 0.905172522010166, 1.23437... | 71,659 |
<p>We are trying to prove a very subtle effect occurring in cells after a certain treatment. Let's assume that the measurements are normally distributed. Let's also assume the untreated cells have $\mu = 1$ and $\sigma = 0.1$ and the treated cells have $\mu = 1.1$ and $\sigma = 0.22$. The question is:</p>
<p>How larg... | 71,660 |
<p>Say you've got a model
$$
y = f(X_1,X_2)+\epsilon
$$</p>
<p>and you're OK with linear (or other parametric) functional forms. Say you think that the effect of $X_1$ on $y$ depends on $X_2$. The standard wisdom is that one should include the main effect of the interaction to capture the effect of $X_1$ on $y$ whe... | 71,661 |
<p>I'm working on a health care dataset that contains one row per member, measuring total number of the member's hospital inpatient (IP) visits during 2012 and 2013. The initial research question of the study asks if the percentage of high IP utilizers (3+ visits per year) in 2013 is statistically significant different... | 71,662 |
<p>I am using a fixed effect model for my panel data (9 years, 1000+ obs), since my Hausman test indicates a value $(Pr>\chi^2)<0.05$. When I add dummy variables for industries that my firms included, they always get omitted. I know there is a big difference when it comes to the DV (disclosure index) among the di... | 46,383 |
<p>If $X$ is a random variable, I would like to be able to calculate something like $$E(e^{-X})$$</p>
<p>How can I do this? Thank you so much.</p> | 71,663 |
<p>I've recently entered the realm of machine learning and a project I am working on requires me to cluster users based on the order they visited webpages on a website. I have data in the form of:</p>
<pre><code>['user_id', 1, 2, 4, 6, 3, 7, 3, 2, 4...]
</code></pre>
<p>Where each number is a category/page that the u... | 71,664 |
<p>I've been stuck on this sample statistics problem for a couple days now:</p>
<p>Assume that two baseball teams have win records of $58\%$ and $54\%$. Demonstrate how to compute or estimate the number of games that must be played in order for the better team to win $70 \%$ of the time, $80\%$ of the time, and $90\%$... | 71,665 |
<p>For some reason I have seen a preponderance of graphs whose color schemes (to represent a continuous variable) transition from red through purple to blue. Here is but one example (from a blog post, but I've seen plenty of published examples):
<img src="http://i.stack.imgur.com/nwTfN.png" alt="http://www.r-bloggers.... | 37,488 |
<p>In the figure below, the stress-strain relationship is linear until they reach their corresponding plastic deformation points (A,B,C,D), beyond these points the relationship deviates from the linearity. The corresponding plastic deformation points shown in solid circles were actually determined by visual inspection ... | 182 |
<p>I try to use a difference-in-difference design in my study. But I have three periods. So I would like to know how I could run my difference-in-difference analysis on Stata with more than two periods.</p> | 33,243 |
<p>I am reading an internal paper that says: </p>
<blockquote>
<p>Let $\sigma^2 V_1$ equal the variance of $\sum_{m\in M}Z_m - Z_0$ and $\sigma^2V_2$ equal the covariance of $||M||^{-1}\sum_{m\in M}Z_m - Z_0$ and $Z_m - Z_0$. </p>
</blockquote>
<p>I am unfamiliar with the notation of the $V$s. Can anyone explain w... | 71,666 |
<p>Is taking the reciprocal helpful in some way, or is it just a matter of historical accident that there came to be two terms to describe the same thing?</p>
<p><img src="http://i.stack.imgur.com/oaPJo.png" alt="enter image description here"></p>
<p>(From the <a href="http://en.wikipedia.org/wiki/Multicollinearity#D... | 71,667 |
<p>I am brushing up on statistics for a data science course.</p>
<p>I saw an example of variables that are highly dependent, but still have 0 covariance (<a href="http://en.wikipedia.org/wiki/Covariance#Uncorrelatedness_and_independence" rel="nofollow">http://en.wikipedia.org/wiki/Covariance#Uncorrelatedness_and_indep... | 71,668 |
<p>Given</p>
<pre><code>score(Q, R) = score obtained by person R for topic Q, where smaller value is better
</code></pre>
<p>In an ideal scenario, I am given a set of data (events are mutually exclusive, $r_n$ scoring well in $q_1$ does not affect scores in $q_2$)</p>
<pre><code>score(1, A) = 40
score(1, B) = 50
sco... | 872 |
<p>I have various sets of irregular interval time series data to which I want to apply some sort of smoothing algorithm to produce a good fit.</p>
<p>I have attempted various methods which all were unsatisfactory.</p>
<ol>
<li>Loess - Too much of a tendency to overshoot/overreact to outliers</li>
<li>Moving Average -... | 44,170 |
<p>I am testing the influence of intramural R&D expenditure, life expectancy, HDP and tax on the GINI index, but I have a problem because I am trying to make my model better by using the Almon model of distributed lag on R&D since the effect of it comes in later years.</p>
<p>I am using R to do my analyses. T... | 33,250 |
<p>This is very basic - </p>
<p>Something is pareto optimal if you can't improve the outcome for one player without worsening the outcome for another.</p>
<p>But what about where one player gets the same but the other player gets more? Is one pareto optimal?</p>
<p>E.g.</p>
<pre>
p1, p2
outcome 1: 2 2
... | 71,669 |
<p>I want to perform multiple linear regression on my variables; since my dependent variable was negatively skewed, I reflected it and then I log transformed it.
My independent variables was positively skewed, so I only log transformed them.</p>
<p>My first question is: <strong>after performing multiple linear regres... | 71,670 |
<p>I'm new to this field and trying to perform some sort of supervised learning with Restricted Boltzmann Machines. I am curious to see whether an RBM can be trained to do the job of an XOR gate? This is a very simple example that can be used to test a typical neural network.</p> | 12,217 |
<p>I want to detect emotions by comparing the cropped lip zone with different templates and output an emotion based on the score.
So far I've applied:</p>
<ol>
<li>Normalization</li>
<li>Discrete and fast Fourier transform</li>
<li>Gaussian blur</li>
<li>Lip-zone cropping</li>
</ol>
<blockquote>
<p><img src="http:... | 33,259 |
<p><img src="http://i.stack.imgur.com/8DhTt.png" alt="enter image description here"></p>
<p>I am attempting previous exams while studying for my own final exam, and can't do this question. I did a-c fine, but am having a lot of trouble doing parts d,e and f. I found a coefficient of 0.5 while equating like terms of ... | 33,263 |
<p>In R, the <code>drop1</code>command outputs something neat.<br>
These two commands should get you some output:<br>
<code>example(step)#-> swiss</code><br>
<code>drop1(lm1, test="F")</code></p>
<p>Mine looks like this: </p>
<pre><code>> drop1(lm1, test="F")
Single term deletions
Model:
Fertility ~ Agricult... | 44,180 |
<p>I have already understood that modeling time dependent covariates should be analog to his:</p>
<pre><code>cfit <- coxph(Surv(tstart, tstop, status) ~ treat + sex + age +
inherit + cluster(id), data=cgd)
</code></pre>
<p>In my dataset, however, the dependent variable has no apart category for 'start' en 'stop'. ... | 71,671 |
<p>I am running an univariate ANOVA in SPSS to test my hypotheses for my 3x2 between subjects design experiment. The factors for the ANOVA are review valence (3 levels) and presence of brand (2 levels). I want to see how these factors affect purchase probability.</p>
<p>I also gathered data for the brand commitment of... | 49,746 |
<p>I am trying to form a polynomial regression model using SVD linear model. As the predictor at a large degree goes too large, say <em>x</em><sup>6</sup>, I first scale it down if the mean of <em>x</em><sup>6</sup> is over a threshold and then put it in the design matrix <em>X</em>. I then can easily get the actual co... | 71,672 |
<p>I had thought that if there is an interaction between 2 independent variables, then it is always the case that there will be main effect for both the independent variables.</p>
<p>However, I found out that this is not the case after reading this <a href="http://courses.washington.edu/smartpsy/interactions.htm" rel=... | 33,267 |
<p>I have a set of points on a grid which is a subset of a larger background set of points on a grid. I would like to test if the subset points are randomly distributed (or not). If it helps, here is the real-world example I am working on:</p>
<p><a href="http://funcgen.vectorbase.org/expression-map/Anopheles_gambia... | 71,673 |
<p>I have a question about how to model text over count data, in particular how could I use the <code>lasso</code> technique to reduce features. </p>
<p>Say I have N online articles and the count of pageviews for each article. I've extracted 1-grams and 2-grams for each article and I wanted to run a regression over th... | 71,674 |
<p>If after a <code>bartlett.test(split(x,list(f1,f2)))</code> I get a very significant <em>p-value</em>, but my sample size is huge -- millions of measurements -- is it justified to discard the homogeneity of variance in case of a significant ANOVA?</p> | 71,675 |
<p>In Stata, how can pseudo <em>R</em> equal one? This is accompanied by blank spaces in standard error and other indicators.
The analysis is binary logistic regression.
What can cause this?</p>
<pre><code>----------------------------------------------------------------------------
F | Odds Ratio Std. E... | 71,676 |
<p>I once read a R example of computing <code>Value-at-Risk</code> and <code>expected shortfall</code> as follows</p>
<pre><code>p = c(0.5,0.1,0.05,0.025,0.01,0.001)
VaR = qnorm(p)
ES = dnorm(qnorm(p))/p
</code></pre>
<p>I am not sure why the expected shortfall can be calculated this way?</p> | 33,271 |
<p>Imagine one loaded dice. Based on EM algorithm, how could we compute how much it loaded if we introduced:</p>
<ol>
<li><p>Variant length on each rolling attempt (look at first and second attempt below 1st one has 6 attempts and second one has 3);</p></li>
<li><p>Uncertainty on seeing each sides value (see-quality, ... | 33,272 |
<p>Consider the following time series plot:</p>
<p><img src="http://i.stack.imgur.com/hrUTb.png" alt="enter image description here"></p>
<p>I am trying to fit a time series to this data. I am using it for the purposes of prediction. What type of time series would work here?</p>
<p>I would like to fit a time series t... | 71,677 |
<p>I have already asked a similar question but did not explain my problem in entirety. Any help would be greatly appreciated!</p>
<p>I am analyzing some data to which I think I need to make some kind of multiple comparisons correction. The data comes from an economic game (Dictator game) and is the form of donations m... | 71,678 |
<p>I am trying to model a sequential exploration-exploitation problem with learning as a multi-armed bandit, where the reward mixes a Markovian and a stochastic reward.</p>
<p>I understand how to model a bandit problem with Markovian rewards. In a Markovian bandit problem, each time the Decision Maker (DM) pulls an ar... | 71,679 |
<p>I have a data set that consists of 52 weeks of data. I want to find the probability that any 10 weeks of data within the set of 52 weeks is close to the mean of the total 52 weeks. </p>
<p>Close meaning whatever measure seems appropriate (whether it is within a standard deviation, or what have you).</p>
<p>I assum... | 71,680 |
<p>I have a time series (five time steps) of samples from a population of the same ~60 individuals, each sample being a haphazardly chosen (i.e. not completely random) subset of the 60. The sample sizes each time ranges from about 15 to up to 50, and the measurement I do for each individual in a sample is a continous v... | 71,681 |
<p>I have a dataset of plant drought tolerance values (called TLP_DRY) that I would like to partition variance for among the nested levels Biome/Study site/Species to figure out whether most variation in TLP_DRY is explained by biome, study site, or species identity. These levels are random effects.</p>
<p>The things ... | 33,275 |
<p>I am analysing sales data of certain products and need to determine if the demand trend is deterministic fluctuating or deterministic stable or stochastic. </p>
<p>How do I do that in R / what approach is usually applied to do so?</p>
<p>Quarterly values would be for example:
2424,3030,3207,2943,2631,2863,2711,28... | 71,682 |
<p>The percentage change between two measurements is usually calculated as $100 \cdot \frac{x_2 - x_1}{x_1}$. If I have confidence intervals $(a_1, b_1)$ for $x_1$ and $(a_2, b_2)$ for $x_2$, is the confidence interval for the percentage change given as $100 \cdot \left ( \frac{a_2 - b_1}{b_1}, \frac{b_2 - a_1}{a_1} \r... | 71,683 |
<p>Are there any R packages that share the similar functionalities of NLTK toolkit?</p> | 71,684 |
<p>I have location data from 5 years (>30,000 points). Each location is given a classification name (in my case vegetation classes). These vegetation classes were assigned by intersecting the locations with vegetation maps representing 5 different years. The vegetation categories changed due to clear cut practices. ... | 71,685 |
<p>I've started using <a href="http://cran.r-project.org/web/packages/lmPerm/index.html" rel="nofollow">lmPerm</a> in order to perform regressions in R.
The equation I want to fit has the form: </p>
<pre><code>out3 <- lmp(outcome ~ bin1 + bin2 + cont1 + cont2, perm="Exact")
</code></pre>
<p>Where "outcome" is a ... | 71,686 |
<p>Maybe the concept, why it's used, and an example.</p> | 71,687 |
<p>Australia is currently having an election and understandably the media reports new political poll results daily. In a country of 22 million what percentage of the population would need to be sampled to get a statistically valid result?</p>
<p>Is it possible that using too large a sample could affect the results, or... | 33,283 |
<p>I am calculating a tolerance interval following <a href="http://www.itl.nist.gov/div898/handbook/prc/section2/prc253.htm" rel="nofollow">http://www.itl.nist.gov/div898/handbook/prc/section2/prc253.htm</a> but this says to multiply the k value by the standard deviation of the sample. I have a model with a fit line, ... | 71,688 |
<p>Inspired by <a href="http://stats.stackexchange.com/questions/25367/grouping-strings-by-common-themes/">this question</a>, I'm wondering whether any work has been done on topic models for large collections of extremely short texts. My intuition is that Twitter should be a natural inspiration for such models. However... | 71,689 |
<p>For all the numerous statistics books out there, surprisingly few seem to cover information theoretic approaches to model selection. Furthermore I cannot find ANY books which cover how implement information theoretic approaches in R. </p>
<p>Does any know of a book which provides a good summary of information theor... | 71,690 |
<p>I don't understand why converting a Bayesian network into a factor graph is good for Bayesian inference?</p>
<p>My questions are:</p>
<ol>
<li>What is the benefit of using factor graph in Bayesian reasoning?</li>
<li>What would happen if we don't use it? </li>
</ol>
<p>Any concrete examples will be appreciated!</... | 71,691 |
<p>You go gambling with a pair of loaded dice. Because of this, your odds of winning are 53% on every throw. Assuming the game pays 2:1 and you keep betting the same amount, how many games do you need to play to ensure an 80% likelihood of winning money?</p>
<p>I am lost with where to start on this problem. I would ap... | 71,692 |
<p>I have 400 instances which must be categorized into 4 classes. Using WEKA, I tried out a couple of multiclass classifiers like J48 and Random Forests, but never made it above Kappa 0.6 and ~65% correctly classified instances (10-fold X-V)</p>
<p>Then I thought about transforming the problem into a 1-vs-all classifi... | 33,287 |
<p>What statistics to use for testing hypothesis about regression coefficient when n is 120.
I plan using a z score but am not sure.</p> | 71,693 |
<p>Suppose that a computer is rated according to three numerical features: processor speed, disk size, main-memory size. Consider three computers $A,B$ and $C$ with values: $$A(3.06,500,6)$$ $$B(2.68, 320,4)$$ $$C(2.92,640,6)$$</p>
<p>The cosine distance emphasizes differences in disk size more than differences in oth... | 71,694 |
<p>I'm analyzing a time series (terms of trades) on which I want to perform a trend estimation by nonparametric methods like the above mentioned. By the way, I'm a total beginner with R and using the help files is already cryptic enough. Using the default settings of R gives me a smoother which simply follows the curve... | 33,291 |
<p>In both ordinal regression and <a href="http://en.wikipedia.org/wiki/Learning_to_rank" rel="nofollow">ranking</a> you are learning from an ordered dependent variables, so my question is:</p>
<p>What is the difference in formulation (if any) between the ordinal regression problem and a learning to rank problem?</p> | 71,695 |
<p><strong>Hi Dear Colleagues,</strong></p>
<p>I wonder how to correctly setup a leave-one-subject-out cross validation (LOSO) for train() function in caret.</p>
<p>Here is my example code:</p>
<pre><code>dat <- as.data.frame(cbind(rnorm(1:500,1),rnorm(1:500,10),rnorm(1:500,5),
rnorm(1:500,100),c(rep('1... | 71,696 |
<p>I have a question concerning data that oscillates between two primary value ranges, and how one might go about determining any performance metrics or abnormalities in that data.</p>
<p>Example:</p>
<p>I have a text file of values that cluster at approximately 6000, and approximately 12000; the low value, and the h... | 71,697 |
<p>I have no formal training in statistics so please correct me if I use the wrong terms as I try to explain my problem.</p>
<p>I have a set of data (less than 80 points) with essentially 1 single outcome (a float we will call <code>dcl</code>) that can potentially depends on 10 of other variables, most of them floats... | 44,216 |
<p>I have data for which I would like to take the log transformation before doing OLS. The data include zeros. Thus, I want to do a log(x + c). I know a traditional c to choose is 1. I am wondering whether there is a way to have the data choose c such that there would be no skew anymore using features like the samp... | 71,698 |
<p>The main goal of my research is to measure the percentage of brown dwarf stars in the Pleiades star forming cluster that are actually double stars (i.e. the brown dwarf star has a companion brown dwarf orbiting it). </p>
<p>To do this, I need to estimate what is the faintest brown dwarf star detectable in our obser... | 12,404 |
<p>I've been working through a few examples of the Jeffreys' prior; however, I'm a little confused by one section. I was hoping that somebody could provide some clarification.</p>
<p>If the Jeffreys' prior is defined as:</p>
<p>$$ \pi_{j}(\theta) = \sqrt{I(\theta)} $$</p>
<p>where $I(\theta) = {\bf E}\left[\left(\fr... | 71,699 |
<p>So I have a data set which I am modeling using the following:</p>
<p><code>model1 <- lm(subject ~ .^2, data=hre.train)</code></p>
<p>This model treats all of the variables as fixed. I want to compare this model to a model which treats all variables as random. Would I use something like:</p>
<p><code>model2<... | 71,700 |
<p>I have two groups (test and control) and I wanted to determine the impact of a certain initiative on the test group. The comparison would be 4-month before the initiative and 4-month after. The starting baselines for the groups are slightly different so to calculate the impact use percentages. If the test group i... | 71,701 |
<p>I have a m x k User-feature matrix (m >> k) obtained by factorizing an original User-websites matrix (m x n) that has #page views as entries. Additionally, there are users (say r) who have been labeled as being part of a particular group. I'm now looking to find a way to see who among the remaining (m-r) users is '... | 71,702 |
<p>If I have two time series $A$ and $B$.
$A$ is dependent on $B$.
I want to forecast future values of $B$.</p>
<p>What statistical techniques should I learn and try?</p>
<p>As an example consider a time series of sales of Apple ipods every month.
Another time series is the number of defects in ipods reported.
Clearl... | 33,303 |
<p>For expectations of random variables (RVs) $X$ and $Y$ it is true that $$E(X+Y)=E(X)+E(Y)$$. My question is whether when conditioning on RV vector $Z_{1...J}$, it is also true that $$E(X+Y|Z_{1...J})=E(X|Z_{1...J})+E(Y|Z_{1...J})$$.
Thanks for enlightening answers!</p> | 71,703 |
<p>I have a dataset for vehicles and trying to predict what will fail. Here is my data set</p>
<pre><code>vId, MileageSincePartLastReplaced, AgeOfPart, TypeOfVehicle, Failure
x,100000,200days,Truck,Alt Belt
y,200000,600days,PCar,Transmission Belt
z,140000,230days,Van,Fan Belt
</code></pre>
<p>Failure is outcome v... | 49,863 |
<p>I know that I should <a href="http://www.unige.ch/math/folks/sardy/Papers/rescaling.pdf" rel="nofollow">standardize my predictors</a> before estimating something like <code>Lasso</code>. But what about the response variable? Do I standardise this as well?</p>
<p>Only concerned with impact on ability for the model t... | 71,704 |
<p>I have a time variable ( time of claim settlement after occurrence ) that may be censored ( claim still open at the moment of observation) and some additional covariates ( line of business, claim size, ...) I am interested to estimate the mean residual life for claims still open. My question is twofold :
1. If I do ... | 33,305 |
<p>I have a dataset that includes race, gender, income, and family size. In addition, a variable for "sliding fee scale" tier is included, which is determined by income and family size. Should income and family size be excluded when fitting data to a logit model? Or should I first include all variables, examine correla... | 33,306 |
<p>My goal is to plot the predicted values generated from a Bayesian model using glmmBUGS run through R. I believe my problem stems from a lack of understanding in 1) how to properly construct a model matrix (R programming problem) because I am not completely sure which values it needs (Bayesian stats problem). </p>
<... | 33,309 |
<p>I have a survey I have conducted on a certain market to determine whether or not we should consider reentering that market.</p>
<p>After conducting the survey I was hoping to draw some conclusions from this including a frequency distribution table of results as well as measures of central tendency and dispersion. <... | 71,705 |
<p>I have a very basic understanding of statistics, and have done many correlations and regressions or simple t-tests, but never an interaction and it is confusing me a bit. I only need to understand the basics of it for now and would really appreciate any input from all you statistics experts.</p>
<p>I just basically... | 71,706 |
<p>For example, the test statistic calculated for the ANOVA test is compared to an F-distribution, while a t-test comparing means compares the test statistic to a t-distribution.</p> | 71,707 |
<p>I am using the nls procedure in R to fit a logistic growth model. In their SSlogis function, José Pinheiro and Douglas Bates chose the formulation</p>
<pre><code> Asym / (1 + exp((xmid-input) / scal))
</code></pre>
<p>for their model. As I am fairly inexperienced with the numerical properties of such models, I won... | 33,315 |
<p>I did an experiment where I asked 13 participants to order 4 stimuli (let's call them stimulus A, B, C and D), so there are 24 possible ways to order 4 items.</p>
<p>Now I would like to know how to analyze this data in the correct way.</p>
<p>Indeed I would like to say that on average a certain order configuration... | 71,708 |
<p>I am having a little trouble with SPSS in a rather complex design. I have to analyze an experiment with 1 within factor and 3 between factors. I don't want to test all possible effects (just the 4 main effects and the 2-way interactions from the between factors), so no interaction effect with the within factor is in... | 33,317 |
<p>I am a bit confused on the term "covariate". It seems like the term can mean two different things. In ANCOVA, the term is used for the third variable that is not directly related to the experiment. For ex: age or IQ on performance study (comparing) between Male and female in Standardized test i.e. IQ is used as a co... | 49,878 |
<p>I have some problems with my BRT analysis. </p>
<p><strong>Introduction to the data:</strong> </p>
<p>The dependent variable is count data of a specific palm species in SA, and the predictors consists of nine various kinds of soil related variables(Mg, Na, Ca, %sand etc.)
The data consist of two data sets with 86 ... | 71,709 |
<p>I am new to GLM modeling but committed to learning as much as possible...</p>
<p>I have the following situation. Data can fall into one of 4 buckets.</p>
<p>It is a GLM model with a poisson distribution and a log link.</p>
<p>The three models can be described as:</p>
<pre><code>1) A A+B A+B+B A+B+B+B
</code>... | 44,242 |
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