question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>Suppose I fit an AR(2) model to a dataset and get the diagnostics. If the Ljung-Box Statistic is significant for all lags for a time series model what is the interpretation of that? Does that mean that the model is not a good fit? Other than this, the ACF of the residuals indicate that they are stationary and normal... | 72,216 |
<p>I have a question about the use of the Fama & French factors. </p>
<p>I’m currently examining possible differences in abnormal earnings between to different type of real estate portfolios. To counter Roll’s (1977) critique on the use of Beta to estimate a portfolio’s degree of outperformance, I will include a ... | 72,217 |
<p>I have the following scenario:</p>
<p>I have two "states". I measure variables $n$ that are affected by the state. A state of 0 is the background state and in this case I expect each variable $n_i$ to be drawn from a normal distribution $N_i$~$(\mu_i,\sigma_i)$ for which I already estimated the parameters. When the... | 34,060 |
<p>I have a first-stage F value of 9 for a model with 1 instrument and 1 endogenous variables, the mechanical rule of thumb of 10 would say my instruments are weak. However, I am reading the 2005 paper by Stock and Yogo, who have tabulated the critical values and I don't understand the interpretation of the following i... | 72,218 |
<p>I'm trying to classify transactions (say credit card transactions) as good or bad without looking at it manually. (The only way to figure out whether a transaction is good or bad is by manually inspecting all the details.) </p>
<p>I've devised certain rules to tag transactions that would not require manual inspecti... | 11,388 |
<p>I would be extremely glad if someone could help me with this.</p>
<p>I'm using the <code>gologit2</code> generalized logistic regression/ partial proportional odds model for ordinal dependent variables. The dependent variable describes firm size and is a categorical variable with three groups, small, medium and lar... | 72,219 |
<p>Currently I am working on my master this which is about excess returns (Sharpe ratio) of Asian REITs. I just transformed all the data in variables which are ready to use in SPSS. In the panel data there are some missing value due to firms which didn’t had a listning in e.g. 2002 but do in 2005. In this case I left ... | 45,101 |
<p>I once heard the following statements about the "correlation" in the context of regression.</p>
<blockquote>
<p>correlation only measures linear relationships</p>
<p>$\text{corr}(X,Y)=0$ does not mean the variables are not related!</p>
</blockquote>
<p>My question is why can't correlation measure non-linear... | 34,063 |
<p>I would like to be able to sample the standard deviation of a multidimensional Gaussian distribution of dimension $n$; that is, given some $\phi$, I would like to sample</p>
<p>$P(\sigma | \phi) \propto \frac{1}{\sigma^n} e^{-\frac{\phi}{2\sigma^2}}$</p>
<p>For high $n$, this distribution is sharply peaked; for my... | 72,220 |
<p>Can someone please help me to verify that AR models with GARCH errors have a positive spectral density and are bounded? </p> | 34,065 |
<p>According to Wikipedia,</p>
<blockquote>
<p>It is also possible to extend Gibbs sampling in various ways. ... It is ... possible to incorporate variables that are not random variables, but whose value is deterministically computed from other variables.</p>
</blockquote>
<p>What is this technique called? What are... | 72,221 |
<p>Let's say I want to do a multiple-sample z-test for proportions. Is there any way to rank them?</p>
<p>How would I compare more than two samples at once?</p> | 72,222 |
<p>I have a problem where I need to calculate linear regression as samples come in. Is there a formula that I can use to get the exponentially weighted moving linear regression? Not sure if that's what you would call it though.</p> | 72,223 |
<p>This is probably demonstrating a fundamental lack of understanding of how partial correlations work.</p>
<p>I have 3 variables, x,y,z. When I control for z, the correlation between x and y increases over the correlation between x and y when z was not controlled for.</p>
<p>Does this make sense? I tend to think tha... | 45,104 |
<p>In a data frame, I would like to get the column's index by name. For example:</p>
<pre><code>x <- data.frame(foo=c('a','b','c'),bar=c(4,5,6),quux=c(4,5,6))
</code></pre>
<p>I want to know the column index for "bar".</p>
<p>I came up with the following but it seems inelegant. Is there a more straightforward b... | 72,224 |
<p>I am traditionally a computer vision guy, and have started doing some self-learning in data mining. I'm having a hard time finding places where these 2 fields converge, as I'd like to get a self-study project that relates the two fields.</p>
<p>where are these areas two used together?</p> | 34,071 |
<p>I have a 2-dimensional panel data set with one characteristic looking along these lines:</p>
<pre><code>individual | year | BMI
1 2005 25.3
1 2006 25.4
1 2007 24.1
2 2005 22.9
2 2006 22.1
2 2007 21.1
...
</code></pre>
<p>I also have annu... | 72,225 |
<p>What are some useful guidelines for testing parameters (i.e. interaction depth, minchild, sample rate, etc.) using GBM?</p>
<p>Let's say I have 70-100 features, a population of 200,000 and I intend to test interaction depth of 3 and 4. Clearly I need to do some testing to see what combination of parameters holds up... | 45,123 |
<p>As the title already states Iam wondering what data exactly are needed from the MATLAB <code>svmstruct</code> to be able to classify a new instance outside of MATLAB, e.g. in python or c++.</p>
<p>I certainly need: </p>
<ul>
<li>the <code>SupportVectors</code> themselves (for calculating the distance using the ke... | 18,620 |
<p>In Statistica one can do a "two series"/bivariate/cross spectrum Fourier analysis to examine the coherency, gain, and phase spectrum across a pair of signals. It is probably a failing on my part, but my attempts to use those search terms to come up with similar values from R have come up blank. What functions/pack... | 45,126 |
<p>What is the optimal case/control ratio in a case-control study? Why do most textbooks or monographs suggest that it is more than 1? Can it be less than 1 (what are the drawbacks?)? Thank you.</p> | 72,226 |
<p>I am using the Zipf-Mandelbrot distribution in my work according to its definition on wikipedia: <a href="http://en.wikipedia.org/wiki/Zipf%E2%80%93Mandelbrot_law" rel="nofollow">http://en.wikipedia.org/wiki/Zipf%E2%80%93Mandelbrot_law</a>.
I would like to obtain the citation of the paper or the book that introduce ... | 72,227 |
<p>I have a Java code that performs a linear regression on a set of data using the Gauss-Jordan elimination. It calculates a linear, quadratic and cubic functions using the least squares method.</p>
<p>My problem is choosing a function out of the three that best models my data. This is ofcourse, without plotting the c... | 34,079 |
<p>I'm trying to do a regression with data over time, and where I suspect there may be a lag component in the relationship between my dependent and independent variables. I've actually found some data online <a href="http://arungaikwad.wordpress.com/2012/03/17/predicting-marketing-campaign-with-r/" rel="nofollow">here... | 72,228 |
<p>I'm trying to measure the reverberation so to speak of a variable - and its effect on itself in the subsequent units of time and its effect on other variables.</p>
<p>For example <code>var1</code> will have an event where it generates 20 units on day one. I'd like to analyze what happens to <code>var1</code> on da... | 72,229 |
<p>I had this example in my machine learning lecture.</p>
<blockquote>
<p>Let $X_2,\ldots,X_n$ be identically distributed (but not independent) copies of $X_1$ drawn from $\mathcal N(0,1)$. Then $X_n$ converges to $Y = -X_1$ as $n \rightarrow \infty$.</p>
</blockquote>
<p>There isn't any explanation for why this se... | 72,230 |
<p>I've got a dataset that I'd like to model, and it seems like the best model would be of the form:</p>
<p>$y = (\beta_1 x_1 + \beta_2 x_2 + \beta_3 x_3) \cdot (\beta_4 x_4 + \beta_5 x_5 + \beta_6 x_6) + \epsilon$.</p>
<p>The $\beta_4$ through $\beta_6$ are independent of each other and have a linear effect on $y$ o... | 72,231 |
<p>Could anyone suggest some statistical measures to describe the distribution of a dendrogram? If I have two dendrograms, how could can I quantify their structural differences?</p> | 72,232 |
<p><strong>Background:</strong></p>
<p>I'm a junior researcher at an institute dealing with regional issues, particularly involving drug policy. Almost two years ago, one of our senior researchers began collecting arrest data about a nearby large city. He had been transcribing newspaper police blotter by hand until I ... | 72,233 |
<p>I do not have a statistical background but I'm trying to understand bayes theorem using a practical example. In my example I plan on using bayes theorem to calculate how often two words occur next to each other. I essentially have some large text and I plan to use the formula before:</p>
<p>Likelihood "this" is fol... | 34,086 |
<p>I would like to draw area-proportional Venn diagrams with 3 sets of data with any free online software. </p>
<p>I tried with eularAPE software but it doesn't work because my 3-set of data do not overlap. My data are: a =45, b=20, c=12, a∩b =9, a∩c =6, b∩c= 1, a∩b∩c= 0. </p>
<p>Is it possible to generate proportion... | 34,087 |
<p>What is the difference between recurrent neural networks and Hopfield networks, or are they same?</p> | 34,089 |
<p>I have completed an meta-analysis of final scores (comparison of means at post test); however, i have noticed that despite being randomised, differences at baseline are present and are biasing the findings. Can I combine co-variate adjusted means (where reported) and final scores means in one meta-synthesis? </p> | 72,234 |
<p>Consider a data set $X$ made up of smaller subsets:
$X=A \cup B \cup C$, with $A,B,C$ disjoint data sets.
Eg:
$A=\{1.0, -1.0, 0\}$,
$B=\{5.0, -7.0, 2.0\}$,
$C=\{1.5, -5.0, 8.0\}$ </p>
<p>Is is possible to transform (scale, shift) $A,B,C$ such that each is individually standardised to have mean=0, and std dev=1... | 72,235 |
<p>I am trying to catch changes in customers sales from week to week using R.</p>
<pre><code>Historical.stats <- ddply(Historical, .(Company,Customer), summarise, mean= mean(Sales), lowerlimit = quantile(Sales,.05) ,higherlimit = quantile(Sales,.95), pval=t.test(Sales,data=Historical)$p.value)
</code></pre>
<p>My ... | 72,236 |
<p>Am testing data from a clinical device, data was extracted using two complementary methods </p>
<pre><code>Method 1: Existing method, 17 variables
Method 2: New method, 13 variables
</code></pre>
<p>I need to quantitatively and visually explain that the <strong>information content / mutual information</strong> o... | 72,237 |
<p>I have been doing some fitting using the fairly standard expression,
$$\chi^2 = \sum_i \frac{(y_{i} - F(x_{i}, \theta))^2}{\sigma_{i}^{2}}$$
where y is my measured data, $\sigma$ is the experimental uncertainty and $\theta$ is the parameter I'm estimating.</p>
<p>I know that in reality my data are not independent a... | 34,090 |
<p>If we have the following histogram:</p>
<p><img src="http://i.stack.imgur.com/HxSwZ.jpg" alt="enter image description here"></p>
<p>And, want to describe it based on one of the following options, which one do you think is correct? Why?</p>
<ol>
<li>positively skewed </li>
<li>symmetric </li>
<li>none of the... | 72,238 |
<p>There are numerous threads in CrossValidated on the topic of model selection and cross validation. Here are a few:</p>
<ul>
<li><a href="http://stats.stackexchange.com/questions/64147/internal-vs-external-cross-validation-and-model-selection">Internal vs external cross-validation and model selection</a></li>
<li>@D... | 72,239 |
<p>A paper asks four research questions which deal with the measurement of latent trait <em>x</em>, a continuous variable which is acquired through learning or practice, and the speed with which the knowledge or skill can be accessed and used in a large group of participants ($n=500$). The first two research questions ... | 72,240 |
<p>We have screening information on thousands of patients followed for several years. We also have their cancer outcomes, whether or not such cancers were identified by screening or were otherwise symptomatic. Exogenous to that question is the question of how people screen. It's a tough question, in general, since ther... | 34,093 |
<p>For heavy-tailed symmetric data, a trimmed mean or other robust estimator of the mean could be a better estimator of the mean than the sample mean. The trimmed mean will be biased for a skewed distribution. What is a robust estimator of the mean that is not biased for a skewed distribution?</p> | 72,241 |
<p>This is probably a silly question, but how can I run ANOVA using only the mean, standard deviation, and the sample size?</p>
<p>i.e.</p>
<pre><code>Group mean sd n
1: 200 5 5
2: 100 22 5
3: 150 14 5
</code></pre>
<p>I am using Statsoft Statistica software.</p>
<p>I know... | 72,242 |
<p>Having read "Restricted Boltzmann Machines for Collaborative Filtering" (Salakhutdinov et. al. 2007), I'm wondering if there has been any follow-up work on applying graphical and/or deep architectures for recommendation engines.</p>
<p>The paper suggests some interesting possible extensions, such as using stacked R... | 72,243 |
<p>I have collected wind speed data for over a year. I want to calculate the mean wind speed using the formula in which the mean speed is the function of the two weibull parameters and the gamma function. How do I evaluate the gamma function in this instant? what do I take as the argument?</p> | 72,244 |
<p>I am working on a project to estimate a radiation protection value called DDREF which is the ratio of two regression coefficients. Specifically:</p>
<p>$DDREF$ $=$ $a/B$</p>
<p>where</p>
<p>$E$ ~ $a*D+B*D^2$</p>
<p>$D$ is dose and $E$ is some outcome, like survival. $a$ and $B$ are coefficients determined by r... | 72,245 |
<p>I'm using Softmax regression for a multi-class classification problem. I don't have equal prior probabilities for each of the classes.</p>
<p>I know from Logistic Regression (softmax regression with 2 classes) that the prior probabilities of the classes is implicitly added to the bias ($\log(p_0/p_1)$). </p>
<p>Us... | 72,246 |
<p>When you toss a coin you get 8 heads and 2 tails. How would you analyze whether a coin is fair? What is the p-value? </p>
<p>The p-value is easy to calculate and it is 56/1024. However I couldn't solve the second part.</p>
<p>In addition, more coins are added to this experiment. Now you have 10 coins. You toss eac... | 72,247 |
<p>I am new user of principal component analysis (PCA) and I have a big doubt.</p>
<p>I have 32 observations with 45 variables and I know that I cannot use the simple PCA for this analysis (n < p). However, I want to use this 32 cases (individuals) for one year (e.g. 2008) and then I would like to create a table wi... | 46,856 |
<p>I have a data set having year-wise monthly average of minimum and maximum temperatures of 32 stations around the country since 1948. The latitude and longitude of the stations are given as well. I have been asked to dig deep into the data set and analyze the much I can. The main objective is to understand the trend ... | 17,170 |
<p>Diagnostic checks of ARMA-GARCH residuals via Box-Ljung tests. I am not sure if I use the correct degrees of freedom.</p>
<p>An arbitrary example: ARMA(0,1)-eGARCH(2,1)-SkewedStudent's-t. </p>
<p>Output:</p>
<pre><code> Estimate Std. Error t value Pr(>|t|)
mu 0.000418 0.000115 3.62471 0.0... | 72,248 |
<p>I have a dataset asking people whether they have been to a certain places (e.g. A, B, C, D), and they can make more than one choice, then a specimen is taken from their nose to see if they are infected with some disease.</p>
<p>I need to find out the relative risk of getting infected for one going to a certain plac... | 34,101 |
<p>I am trying to calculate the relative risk for being tested as positive for people aged >25 or <=25, and here is the result.</p>
<pre><code>$data
Negative Positive Total
>25 115 11 126
<=25 117 3 120
Total 232 14 246
$measure
risk ratio with ... | 72,249 |
<p>I have 2 million (<em>user</em>, <em>item</em>, <em>category</em>, <em>score</em>) tuples, where users give 0/1 scores to items that belong to categories. I want to convert these to a set of (<em>user</em>, <em>category</em>, <em>affinity</em>) tuples, using the items linking a user and a category to calculate that ... | 72,250 |
<p>In a problem I am working on, I have two random variables, X and Y. I need to figure out how closely correlated the two of them are, but they are of different dimensions. The rank of the row space of X is 4350, and the rank of the row space of Y is substantially larger, in the tens of thousands. Both X and Y have th... | 72,251 |
<p>I'm doing a psychology project and I'm struggling with statistics (SPSS) especially on meditational analysis. I have searched all over my notes from my bachelor degree but there is nothing on meditational analyses whatsoever. There were hardly any steps shown, only results are provided in all the journals I read fro... | 72,252 |
<p>Let $X(t)$ be a non-stationary continuous time-dependent random process with a known model but unknown parameters.</p>
<p>I'd like to know if it's possible to estimate the parameters of $X(t)$ not by using different observations of the same run at different instants $t$, but rather by observing different runs at di... | 72,253 |
<p>let consider following probability distributions</p>
<pre><code>X P Q Kullback Kullback_divergence
1 0.526810511 0.6557 -0.166341349 11.97922287
2 0.213080233 0.0357 0.54919316
3 0.02600177 0.8491 -0.130769473 ... | 34,107 |
<p>Let $z$ a random variable with PDF : $f_z= Cz^{k-1}(1-\frac{z}{d})^bF(-a+k+1,b;b+1;1-\frac{z}{d})$, where $0\leq z \leq d$, $F$ is the Hypergeometric function, $k$ is a positive integer, $-a+k+1 >0$, $C$ is a constant and $a ,b$ are 2 real positive numbers.</p>
<p>Please I need to compute a closed form of the M... | 72,254 |
<p>I wish to perform Jeffries-Matusita distance on 14 spectral bands. Is there anyone who can help with how it is done in R? Thank you.</p> | 34,108 |
<p>I have used the R lme function (nlme package) to construct linear mixed models, with a single random effect (as a random intercept) and a varIdent variance structure on a fixed effect (that is a factor). </p>
<p>The data is from a commercial fishery and I am looking to see which are the most important variables tha... | 72,255 |
<p>I'm accumulating a lot of vital signs from emergency department patients, and would like to assess if different features yield significantly different distributions.</p>
<p>Eg. for heart rate I have 888.424 measurements (stored in all_hr) for all patients and 321.357 measurements for geriatric patients (stored in g... | 976 |
<p>This is similar to an earlier question which was never answered... <a href="http://stats.stackexchange.com/questions/85393/interpretation-of-interactions-between-categorical-data">Interpretation of interactions between categorical data</a>... and which is much shorter so no problem if you would like to read/answer t... | 72,256 |
<p>I did a study in which I wanted to see if a teaching intervention would have an effect on student learning. I nonrandomly divided students into two groups, a control and experimental group, and gave them all a pretest at the beginning of class and a postest at the end.
Since there are both between and within groups ... | 72,257 |
<p>I have a set of discrete points on a 2D surface and need to build a heat map or a distribution of the density of the points. However, I also need to smooth out the density/distribution by applying some sort of kernel (Gaussian kernel, for example).</p>
<p>I Know what Gaussian distribution is, and I have no idea how... | 34,113 |
<p>I have a biological dataset with 30.000 features (genes) and 1000 data points (cells).
Basically I have two major classes of cells: 1 and 0 with a distribution of 90/10.</p>
<p>Now I am trying to classify these correctly using nested cross validation.
The first thing I tried was to manually decrease the number of... | 72,258 |
<p>I have the data as following:</p>
<pre><code>rating document1 document2
5 some words some words
3 some words some words
2 some words some words
</code></pre>
<p>First column is user rating, and other two are the user feedback, which is a cocument. Also, i have <code>category</code> is a... | 72,259 |
<p>I have the following model:
$$
|X| = B_0 +B_1 \cdot y + B_2 \cdot z ,
$$
where $z$ and $y$ are normally distributed random variables, and $B_1$ and $B_2$ denote the coefficients. </p>
<p>My dependent variable contains either the positive or negative values of $X$. The positive and negative values of $X$ together ar... | 34,115 |
<p>Despite my readings (on stack <a href="http://stats.stackexchange.com/questions/27750/feature-selection-and-cross-validation">1</a>, <a href="http://stats.stackexchange.com/questions/2306/feature-selection-for-final-model-when-performing-cross-validation-in-machine">2</a>, or in literature (Cawley, 2010; Japkowicz, ... | 72,260 |
<p>Male exam scores
58
54
61
64
60
60
45
44
53
54
32
56
43
69
69
72
66
45
63
49
48
53</p>
<p>Female exam scores
71
55
42
49
57
51
51
60
60
60
51
43
41
24
43
48
57
79
73
53
53
64
54
59
73
47</p> | 72,261 |
<p>Im trying to calculate the mortality rates for males and females in two different disease groups (type 1 and type 2 diabetes). </p>
<p>In my primary analyses i forgot to use respective gender as the background population and instead used the whole populationen. </p>
<p>Now the thing is when i divide the background... | 72,262 |
<p>I am currently using the <code>evd</code> package which fits a two-parameter GPD by maximum likelihood.
Since in small samples the MOM is superior to the ML estimation I'd like to give it a go. However, the POT package - which could do the job - is offline due to memory access errors.</p>
<p>There are many extreme ... | 34,120 |
<p>I have some data which are strongly gathered into more than one cluster. I am looking for a term to effectively describe this phenomenon: e.g., <em>multi-clustered data</em>, which however seems to me that we have later imposed a cluster analysis to identify more than one cluster. So far I prefer <em>multi-polarised... | 72,263 |
<p>All the Species Distribution Modelling literature suggests that when predicting the presence/absence of a species using a model that outputs probabilities (e.g., RandomForests), choice of the threshold probabilitiy by which to actually classify a species as presence or absence is important and one should not always ... | 72,264 |
<p>I have 3(treatment)x3(period)x6(sequence) crossover design data. I have used SAS PROC MIXED procedure and I got the results with following code:</p>
<pre><code>data cross;
input yield id treatment period sequence;
cards;
72 1 1 1 1
73 1 2 2 1
77 1 3 3 1
75 2 2 1 2
78 2 3 2 2
70 2... | 37,974 |
<p>Can we use ordinal/multilevel predictors directly into binary logistic regression model?</p>
<p>I guess not.</p>
<p>we usually here convert them to multiple predictors to have values 1/0 for each category.</p>
<p>Also if we have a variable with say 20 levels(e.g. sectors like 'energy' 'IT' 'telecom')
or factors,... | 34,122 |
<p>Is it recommented to delete the cases from a database if the responses are highly incomplete? Is there a percentage that can be taken into consideration? (for example, deleting a case if more than 50% of the items have not been answered).</p> | 72,265 |
<p>I did multiple regression analysis, and i have one little problem about interpreting the output. What does McFadden R-Square means, if it is 0,196. What it shows me? Is Mcfadden the best solution, or should i watch others like Nagelkerke or Cox and Snell. What`s the difference between the three of them (beside value... | 45,184 |
<p>I am running kmeans for a market research study, and I have a couple of questions:</p>
<ol>
<li><p>Should I be standardizing my data, and if so, how? For example, one variable I have is product demand, which is measured on a seven point scale. On the other hand, I also have a variable on age, which is a very differ... | 45,185 |
<p>Say I have 10 subjects, coming from three groups. In each subject I make two measurements (one on the left, one on the right).</p>
<pre><code>ID <- rep(1:10, 2)
myData <- data.frame(ID)
myData$Group <- rep(c('A','B'), 10)
myData$Measurement <- rnorm(20, mean = 10, sd = 1)
myData$MeasurementLocation... | 72,266 |
<p>I am looking for help in defining my problem.</p>
<p>Essentially, I have two data processes (both continuous macroeconomic variables: $x$ and $y$). There is evidence of bidirectional causality between $x$ and $y$, proven by a Granger Causality test.</p>
<p>What I am alleging now is that $x$ and $y$ are not causing... | 34,123 |
<p>My question is a really simple one but those are the ones that really get me :)
I don't really know how to evaluate if a specific time series is to be decomposed using an additive or a multiplicative decomposition method. I know there are visual cues as to telling them apart from one another but i don't get them.</... | 34,124 |
<p>I'm trying to run an SV model against prices of Euro/USD. For those not familiar with SV, its a volatility model in which each point gets its own volatility parameter $h_t$ with 3 main parameters that are derived using a monte carlo simulation (MCMC),</p>
<ul>
<li>$\mu$ = average of the volatility across the entire... | 72,267 |
<p><img src="http://i.stack.imgur.com/z71AL.jpg" alt="enter image description here">
My data consists of one column of real temperature, and one column of calculated temperatures. I want a single number which quantifies the 'bias' in the real temperatures.</p>
<p>Basically, if most of my data points lie below the ref ... | 72,268 |
<p>I have a tree of states and I would like to sample from this tree based on pure birth process; however, I don't know how exactly I can do this; </p>
<p>so far I have done this; I simplified my problem; the probability of the first state is $A$ and each state obtain the parent probability minus $e^{-\lambda}$;</p>
... | 34,126 |
<p>Normally, a <a href="http://en.wikipedia.org/wiki/L%C3%A9vy_process" rel="nofollow">Lévy process</a>, $X_t$, is defined for $t\geq 0$, so $t_0=0$. I am applying a transformation on the time index so that it starts from a negative value instead of zero. </p>
<p>Now, is it possible to define a Lévy process with $t_... | 72,269 |
<p>Which test to rely on for a time series data of 30 years for instance(when they offer different cointegrating equations in Johansen's cointegration test)? Trace test or maximum eigen value? </p>
<p>Say trace test says there are 8 cointegrating equations. Is this the number we input in the "number of cointegrating" ... | 34,129 |
<p>I am reviewing some papers relating school performance to socio-economic background:</p>
<ul>
<li><a href="http://archive.treasury.gov.au/documents/1421/HTML/docshell.asp?URL=05%20How%20much%20of%20the%20variation%20in%20Literacy%20and%20Numeracy%20can%20be%20explained%20by%20School%20Performance.htm" rel="nofollow... | 72,270 |
<p>I have a data set with only discrete/rounded values in it. As a result, when I produce a Q-Q plot a "stair-case" pattern appears. Can I still interpret this just like a normal Q-Q plot even though it is a lot harder to do so? Are there any limitations to interpreting a plot like this?</p> | 72,271 |
<p>I would like to regress total energy expenditure on weight and gender. Is it better to consider gender as a dummy variable or find separate regression equations for men and women?</p> | 72,272 |
<p>I have response variable count data that should be treated as quasipoisson or something similar. This data also contains outliers which are important to the dataset. I cannot find an r package that will let me do robust regression with quasipoisson-type distribution. I could, however, collect weights for each mod... | 72,273 |
<p>Is there a way to get the variance of prediction for a linear regression model in R? The variance that I need is $s_f^2=s^2\left(1+\frac{1}{n}+\frac{(x_{n+1}-\bar{x})^2}{\sum_{i=1}^n (x_i-\bar{x})^2}\right)$.</p> | 72,274 |
<p>I have a sample of data that follows a certain distribution with known parameters. How can I estimate the confidence interval based on this sample, without using the quantile function?</p> | 34,131 |
<p>I am having some strange results in a regression I am trying to run and I hope someone can help me to interpret them. Basically, first I regressed my dependent variable on a set of regressors which were all significant, then I added a control and some of them became not significant anymore. So far so good, I expl... | 114 |
<p>Based on $N$ realizations of two random variables $X \sim N(0,\sigma_X^2)$ and $Y \sim N(0, \sigma_Y^2)$ with correlation $\rho$, I conduct a simple linear regression $Y = \beta_0 + X\beta_1 + \epsilon$.</p>
<p>Using the known distributions of $X$ and $Y$, their correlation $\rho$ and the number of realizations $N$... | 72,275 |
<p>I guess this issue must be somehow cliched, yet I wasn't able to find the answer that would satisfy me.
The key role of statistics and econometrics is to make inference about population using some sample data. Working on the data which encompasses entire population (which is normally a case in any company we have a... | 49,321 |
<p>A contractor has submitted bid on four state jobs: a car parking garage, an office building, a theater, and a shopping mall. State rules do not allow a contractor to be offered more than one of these jobs. If this contractor is awarded any of these jobs, the profits earned from these contracts are: RM2 million from ... | 72,276 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/27786/analysis-of-part-of-likert-scale">Analysis of part of Likert scale</a> </p>
</blockquote>
<p>My survey consist of 6 airlines (non metric) and 10 attributes for rating these airlines. The questionnair... | 49,891 |
<p>In order to explain why I have those stupid question you'll find below I have to say that I am more a machine-learning person. While I worked on problems in bioinformatics everything was fine. When I heard words like "regression" or "kurtosis and skewness", in first case I just smiled, in second case I just made som... | 72,277 |
<p>The relative asymptotic power of non-parametric tests is reported to be high. What is the power of tests such as Wilcoxon Signed Rank Test and Mann-Whitney U with N's of 10, 20, 50, for example, as compared with t-tests?</p> | 45,209 |
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