question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>I have a question relative to the correct method to deal with univariate outliers when one has to conduct an ANOVA.</p>
<p>Starting with an example, suppose I have two samples of subjects tested on a number of dependent variables. For each dependent variable I run an ANOVA with group as independent variable. Suppos... | 70,511 |
<p>I am going to write a regression model including an interaction between X and factor Z, but there is evidence that there is no interaction between them.</p>
<p>Shall I put the interaction coefficients in to the model to predict Y or not?</p> | 1,847 |
<p>I am empirically studying Fama & French three factors (market, SMB, HML - independent variables) model on a Viet Nam stock exchange. The dataset is daily stocks' return during almost 4 years. The stocks are grouped in six portfolios - each is dependent variable in each regression. I would like to test the validi... | 31,526 |
<p>While reading <a href="http://rads.stackoverflow.com/amzn/click/0387848576" rel="nofollow">The Elements of Statistical Learning</a>, I've encountered the term "point-wise variance" several times. While I have a vague idea of what it likely means, I'd be grateful to know</p>
<ul>
<li>How is it defined?</li>
<li>How ... | 42,047 |
<p>I don't understand what the answers say</p>
<p>The transition matrix is</p>
<p>$$
\begin{pmatrix} 0.5 & 0.5 & 0 \\ 0 & 0.5 & 0.5\\ 0 & 0 & 1 \end{pmatrix}
$$</p>
<p>In the answers it says:</p>
<p>$C_1 = \{3\}, T = \{1,2\}$, state 3 is aperiodic because $p_{33} > 0$ and recurrent. State... | 31,527 |
<p>I am working on a problem where it is expensive to label data and I have sampled a small subset of the available data and labeled it.</p>
<p>My classifier is a binary classifier that I use with the hope of removing samples that are "false" but keep samples that are "true".</p>
<p>My question is: how well does the ... | 1,859 |
<p>I have been working on a problem where I would like to estimate a particular probability. Namely, the problem has to deal with estimating the probability that an element $a$ in a structure $A$ can be substituted for an element $b$ in structure $B$ (think genes and DNA or words and documents).</p>
<p>That is.</p>
<... | 70,512 |
<p>I have a regression of costs on volume and some interactions (costs ~ volume + volume:year + year)</p>
<p>Often times when I do a regression, I expect a negatively sloped relationship and the model validates that. I can add up the volume coefficient and the associated interaction term for a given point and get a n... | 31,531 |
<p>I am attempting to estimate the effect of various variables on the time-series of counts of reported cattle stillbirths. We investigate the effect of day-of-week, month, holidays etc…and also the effect of non-temporal variables.</p>
<p>We performed model comparisons between Gaussian glm, Poisson glm and negbin glm... | 1,863 |
<p><strong>Background:</strong></p>
<p>I have estimated a model using panel data with the Arellano Bond estimator (see e.g., <a href="http://www.fordham.edu/economics/mcleod/Elitz-usingArellano%E2%80%93BondGMMEstimators.pdf" rel="nofollow">http://www.fordham.edu/economics/mcleod/Elitz-usingArellano%E2%80%93BondGMMEsti... | 1,864 |
<p>I want to compute the p-value of a single numeric value drawn from an arbirtary distribution.
The p-value should be comparable to p-values that have been computed with single distinict values drawn from sets (using the Chi-Square Test).
The distribution of the numeric data is propbably mostly normal distributed, but... | 70,513 |
<p>The price of a product has signficant impact on the total sales. Hence modeling sales would give the incentive to include price as a regressor (amongst other variables). Suppose we would estimate this using OLS, this gives something like</p>
<p>$sales_t=\alpha_0+\beta_1\times price_t+...+\epsilon_t\;\;\;\;\;\;\;\;\... | 31,535 |
<p>I saw from the lecture that
$$E[X|X]=X$$</p>
<p>where $X$ is a random variable.
But when I am trying to prove it formally, I cannot reach to this conclusion.
$$E[X|X]=\int{xf_{x|x}(x) dx}=\int{xf_{x,x}(x)/f_x(x)dx}$$
$$=\int{xf_x(x)/f_x(x)dx}=\int{xdx}=x^2/2$$</p>
<p>What am I doing wrong?</p> | 70,514 |
<p>I just made an implementation of P(A|B)/P(¬A|B) for a "people who bought this also bought..." algorithm.</p>
<p>I'm doing it by </p>
<pre><code>P(A|B) = count_users(bought_A_and_B)/count_users(bought_A)
P(¬A|B) = count_users(bought_B_but_not_A)/count_users(did_not_buy_A)
</code></pre>
<p>Then dividing the top one... | 31,537 |
<p>I need to use Random Forest in my experiments. Although using the same training and test datasets, each time that I train the Random Forest on my training set, I get a different result on my test set. I know that this variation is due the randomness in the algorithm. But how can I decrease that? What is the correct ... | 31,538 |
<p>What are some valuable Statistical Analysis open source projects available right now?</p>
<p>Edit: as pointed out by Sharpie, valuable could mean helping you get things done faster or more cheaply.</p> | 49,316 |
<p>Suppose I have a random variable $X$ ~ $Unif(0,\theta)$ where I want to estimate $\theta$. I draw a sample $X_1,...,X_n$.One way is to get a point estimate using e.g. maximum likelihood estimation via the sufficient statistic $X_{(n)}$.</p>
<p>However, suppose I want a 95% confidence interval of sorts on the value... | 70,515 |
<p>I am using R to fit a linear model. </p>
<p>My code is:</p>
<blockquote>
<p>rating_lm <- lm(rating\$flow ~ I(rating\$raw^2) + rating\$raw, data = rating, weights = 1/(rating\$flow)</p>
</blockquote>
<p>I then use the following code to get prediction intervals:</p>
<pre><code>b <- predict(rating_lm, inter... | 70,516 |
<p>I came across the following statement</p>
<blockquote>
<p>$cov(E(\mathbf{z}|y))$ is degenerate in all direction orthogonal to $Span(\mathbf{x}_1, ...,\mathbf{x}_K)$</p>
</blockquote>
<p>Vector $\mathbf{z}$ is a centred random vector of size $p$, $y$ is a scalar random variable and the $\mathbf{x}_k$ are $K$ vect... | 70,517 |
<p>I have a sample of 48. According to the central limit theorem, I may consider means of every continuous variable in my sample to have a normal distribution.
However, one variable has a mean of 14 +/- 8 and when I draw a normal quantile plot, it seems to not be a normal distribution. If I use a t-test to compare this... | 70,518 |
<p>I have a dataset (<code>data.mrsa</code>) about the MRSA prevalence of elderly in long term care facilities (LTCF) with the following information:</p>
<ul>
<li>mrsa_result: MRSA result of recruited elderly (positive VS negative)</li>
<li>age: residents' age</li>
<li>ltcf: UID for each LTCF (we sampled 30 out of 100... | 42,067 |
<p>I have a few variables, $A$, $B$, $C$, $D$, and $E$. To find their cointegration coefficients, $A$ is regressed against $B$, $C$, $D$, and $E$.
$$
A = W_b * B + W_c * C + W_d * D + W_e * E + W0 $$
(where $W_b$, $W_c$, $W_d$, $W_e$ are cointegration coefficients and $W_0$ is intercept). The residuals are then tested ... | 70,519 |
<p>I have two distinct data samples($A$ and $B$), and to each one a gaussian is fitted. I then evaluate the product $S = \sigma_A * \sigma_B$ ($\sigma_A$ and $\sigma_B$ and their errors are obtained from fit procedure). </p>
<p>If I assume $\sigma_A$ and $\sigma_B$ are uncorrelated, I can easily propagated the err... | 70,520 |
<p>In R, the function <code>skewness</code> from package <code>moments</code> allows one to calculate the skewness of the distribution from a given sample. Does anybody know if there is a ready-to-use function to calculate the skewness of the distribution from a given <em>histogram</em>?</p> | 70,521 |
<p>I have some data from purchase transactions of a drug and I want to assess any time trend. The data contain the unit price, date of transaction, name of supplier and name of institution that bought the drug. Since the unit price may depend on who the supplier is but perhaps who bought the drug (special deals between... | 70,522 |
<p>I am facing the following problem: I have a training sample and estimate a model on that training sample. My model is simply OLS: $y_t = a + \beta x_t + \varepsilon_t$. The model is estimated on points in set $t\in T$. The training sample contains well behaved data. When forecasting with this model out of sample, th... | 70,523 |
<p>I have a data set of cell phone customer information data with twocolumns. The first column contains the certain category that an account falls in (either A, B or C) and second column contains is binary valued for whether that account has cancelled. eg</p>
<pre><code>A | cancelled
C | active
B | active
A | cance... | 70,524 |
<p>I've got a series of statistics computed on different populations of cells, where each population contains a different genetic deletion.
The measurements I have for each population involve GFP intensity: median intensity, mean intensity, median absolute deviation of intensity, max intensity and min intensity.<br>
I... | 70,525 |
<p>I'm trying to visualize a matrix of 3 datasets.<sup>*</sup> For the sake of example, let's say I have a list of hats, coats and shoes, and I want to display a 2D grid/visualization of each possible combination.</p>
<p>Is it even possible without turning it into a 5x25 grid?</p>
<p>I had a look at this thread:
<a h... | 31,548 |
<p>I'm trying to approximate a variable 'lag', measured in days until a certain event happens. My dataset is balanced in that, for half of the observations, 'lag' is not a number (ie. the event never happens).</p>
<p>How do I transform this variable in a way that doesn't introduce noise (ie. setting it to 0)?</p> | 70,526 |
<p>Given a set of data (~5000 values) I'd like to draw random samples from the same distribution as the original data. The problem is there is no way to know for sure what distribution the original data comes from. </p>
<p>It makes sense to use normal distribution in my case, although I'd like to be able to motivate t... | 70,527 |
<p>Suppose I will be getting some samples from a binomial distribution. One way to model my prior knowledge is with a Beta distribution with parameters $\alpha$ and $\beta$. As I understand it, this is equivalent to having seen "heads" $\alpha$ times in $\alpha + \beta$ trials. As such, a nice shortcut to doing the ... | 70,528 |
<p>I ran across this density the other day. Has someone given this a name?</p>
<p>$f(x) = \log(1 + x^{-2}) / 2\pi$</p>
<p>The density is infinite at the origin and it also has fat tails. I saw it used as a prior distribution in a context where many observations were expected to be small, though large values were ex... | 70,529 |
<p>How can I forecast using Arima/Garch model. Can you explain that step by step with an example?
For example: if I have stock prices, I fit an ARIMA (SPSS), save the residuals, test for ARCH effects (Gretl).
Now my problem is that how do I put the data set together and how will I forecast in SPSS or Gretl using the ... | 70,530 |
<p>I use the <code>plsr</code> formula in R and the oscorespls algoritm for analysing my datasets. The datasets are characterized by relatively few number of observations (22), one response variable and different numbers of predictors (from only analysing 4 predictors and upwards). However, it is difficult to choose th... | 31,555 |
<p>I have a 7 points dataset that looks like this:</p>
<pre><code>dates <- as.Date(sprintf('2011-01-%s', 15:21))
vals <- c(0.05816136, 0.31020050, 0.45542547, 0.52401006, 0.56796386, 0.59687058, 0.61741189)
dat <- data.frame(date=dates, val=vals)
plot(dat$date, dat$val, type='b')
</code></pre>
<p>The plot... | 98 |
<p>I am an ecologist that has counted 11 different species of herbivores in about 110 blocks of two habitat types over 18 months, and I am interested in predicting the density across the study area from the model I hope to make. The approach so far is to build a spatially smoothed GLM, accounting for the over-dispersio... | 70,531 |
<p>I have applied ANOVA on 3 independent groups of unequal sample sizes. I doubt that the ANOVA result are showing Type 1 error because of heteroscedasticity in data points (checked using F-test as well as Bartlett's test). I want to know is there any other good statistical method to solve this problem other than the t... | 70,532 |
<p>Background: I have an $n \times m$ matrix with count data. The rows contain $n$ semantic categories (in my case 19). Each column contains 10 entries and each entry is assigned to one row category (row). The row margin totals give an estimate of the relative occurrence of each category (row). </p>
<pre><code> |... | 31,558 |
<p>This is in part motivated by the following <a href="http://stats.stackexchange.com/questions/37569/lognormal-distribution-from-world-bank-quintiles-ppp-data">question</a> and the discussion following it. </p>
<p>Suppose the iid sample is observed, $X_i\sim F(x,\theta)$. The goal is to estimate $\theta$. But origina... | 922 |
<p>Suppose that
$E[T]=E[\gamma_i|X_1]+E[e_2|X_1]$ (1)
where $\gamma_i$ and $e_2$ are distributed uniformly on the interval [0,1].
$X_1= \gamma_i + e_1$ </p>
<p>So the background is that im trying to find $E[X_2|X1]$ and since $X_2=\gamma_i+e_2$ i expand it to the equation that appears at the start of the question.
... | 36,451 |
<p>I have several study sites, 4 from 2009, 2 from 2010, and 5 from 2011, for a total of 11 sites. At each site, I have 3 quadrats (defined unit of space), and within each quadrat I placed 25 live oysters (75 then at each site). After 1 year, I went back to see how many I could find alive and dead, and then was able to... | 70,533 |
<p>I need to do reliability analysis on computerized test questions. Given a multiple choice question, if 20/25 got it right the first time the test was given, 22/30 the second time the test was given, 15/22 the third time the test was given, and 14/23 the fourth time the test was given, I want to determine if all of ... | 42,089 |
<p>For a disease that I am interested in, five or six published works of research have shown an association of changes in gene expression with presence of the disease. However, all these diagnostic biomarker studies were performed with small numbers of cases (15-30) and controls (15-30), and the overlaps between their ... | 70,534 |
<p>I have data set which theoretically is a Gaussian curve . My dataset looks like this:</p>
<p><img src="http://i.stack.imgur.com/v8y0A.gif" alt="enter image description here"></p>
<p>To find the peak I looked for the maxima in data set. Now this has two parts and off pulse part which is noise, and an on pulse part... | 31,561 |
<p>I am kind of at my wits end for this proof. Given $Y$ is Gamma with parameters $\alpha$ and $\beta$, the MGF is given by $(1-\beta t)^{-\alpha}$. I need to find mean, variance and skewness. So I managed to derive the mean and variance, but cannot prove the result for skewness.</p>
<p>Given the MGF, I calculate 1st,... | 70,535 |
<p>I need to simulate some microarray experiment datasets. I have the levels of expression of a set of synthetic genes in different experimental conditions. For simplicity of the method this levels are relative intensities (0%-100%). I want to use the error model developed by Rocke et al. (link below):</p>
<p>$y=\alph... | 70,536 |
<p>Consider the criterion function for ordinary least squares
$$
S(b)=(Y-X'b)'(Y-X'b)
$$
with Y, a matrix of dependent variables, and X, a matrix of explanatory variables. It is of course known that:
$$
\frac{\partial S}{\partial \beta} = -2\cdot X'Y+2\cdot X'X\cdot b
$$
solving for $b$ yields the OLS estimator for $... | 70,537 |
<p>Suppose I have a coin toss experiment in which I want to calculate the maximum likelihood estimate of the coin parameter $p$ when tossing the coin $n$ times. After calculating the derivative of the binomial likelihood function $ L(p) = { n \choose x } p^x (1-p)^{n-x} $, I get the optimal value for $p$ to be $p^{*} =... | 70,538 |
<p>This seems like a trivial question yet my lack of distributed training is leading me towards potentially more confusing answers. Hence I would like to field my question here:</p>
<p>I have data on several hundreds of thousands of survey respondents who received health care in 2011 and demographic information on the... | 31,563 |
<p>Pearson correlation coefficient is calculated using the formula $r = \frac{cov(X,Y)}{\sqrt{var(X)} \sqrt{var(Y)}}$. How does this formula contain the information that the two variates $X$ and $Y$ are correlated or not? Or, how do we get this formula for the correlation coefficient?</p> | 31,565 |
<p>What is a good and relatively brief overview of good practice for getting valid results from surveys. </p>
<p>I'm particularly interested in something about good survey design and analysis. </p> | 31,567 |
<p>I am a programmer who, in a past life, used the products RS/1, RS/Explore, and RS/Discover in a manufacturing engineer career. Now, years later, I would like to do some multivariate regression on some real-world data (sales data from my wife's store). The point would be to highlight what sales days are truly excep... | 42,096 |
<p>Some edits made...</p>
<p>This question is just for fun, so if it isn't fun then please feel free to ignore it. I already get a lot of help from this site so I don't want to bite the hand that feeds me. It's based on a real life example and it's just something I've wondered about a lot.</p>
<p>I visit my local doj... | 70,539 |
<p>I have two exclusive groups of people and a counter of how many events happened for each group.</p>
<p>Lets say group 1 has 7000 people and group 2 has 3000 people.
group 1 had 50 events and group 2 had 40 events.</p>
<p>I'm calculating the event percentage for each group for example for group1 its 50/7000. for g... | 42,100 |
<p>I would like to find out the values <code>(x, y)</code> used in plotting <code>plot(b, seWithMean=TRUE)</code> in <strong>mgcv</strong> package. Does anyone know how I can extract or compute these values?</p>
<p>Here is an example: </p>
<pre><code>library(mgcv)
set.seed(0)
dat <- gamSim(1, n=400, dist="normal... | 42,103 |
<p>This question might be way off base as I am just getting to know vector autoregressive models, but I've tried searching through the usual channels and if this actually is a valid question it might be of help to others that it is here.</p>
<p>Should I think in the same way about sample size for a VAR-model as for an... | 70,540 |
<p>I conducted a chi square test using crosstabs and found that there is a significant difference (p=0.020), but the post hoc showed that all the std residual were between -1.96 and 1.96. How to interpret these result? Do I have to conclude the result is still not significant?</p> | 31,568 |
<blockquote>
<p>A Poisson variable $Y_i$ is believed to depend on a covariate $x_i$ and it is propsed that log-linear model with a systematic component $a + bx_i$ is appropriate. In an experiment the following values were observed:</p>
<p><em>values not important to question</em></p>
<p>Write down the log-l... | 42,105 |
<p>This isn't as easy to Google as some other things as, to be clear, I'm not talking about logistic regression in the sense of using regression to predict categorical variables.</p>
<p>I'm talking about fitting a logistic growth curve to given data points. To be specific, $x$ is a given year from 1958 to 2012 and $y$... | 70,541 |
<p>I am trying to learn statistics because I find that it is so prevalent that it prohibits me from learning some things if I don't understand it properly. I am having trouble understanding this notion of a sampling distribution of the sample means. I can't understand the way some books and sites have explained it. I t... | 39,994 |
<p>I understand the basic principles involved in Kalman filtering and I have spend some time implementing several algorithms in Matlab. The problem I'm facing now is to check if the algorithm and my code actually do the right thing. I know that there are statistical tests, such as the NEES test (= normalized estimation... | 70,542 |
<p>I was looking up the Wikipedia page on <a href="http://en.wikipedia.org/wiki/Sampling_distribution" rel="nofollow">Sampling distribution</a> and the first paragraph makes the claim:</p>
<blockquote>
<p>allow analytical considerations to be based on the sampling distribution of a statistic, rather than on the join... | 42,116 |
<p>Suppose we have two mouse strains S1 and S2 and we have already tested the effect of two different conditions (say treatment vs. control) on the level of gene expression of any strain, each experiment with several replicates.</p>
<p>Now we are looking for the genes that are for example significantly higher expresse... | 70,543 |
<p>Can we run this regression:</p>
<p>$Y_{it} = a + bX_{it} + c_2Time_2 + ... + c_TTime_T + ht + U_{it}$ </p>
<p>$i = 1,2,..., N;$ $t = 1,2,3...,T$</p>
<p>Where
</p>
<ul>
<li>$Time_T$ are time dummies </li>
<li>$t$ is the time trend.</li>
</ul>
<p>In other words, can we run a regression with b... | 31,572 |
<p>I have two vectors, $X$ and $Y$ of equal length $n$. Basically, I want to match up each value from $X$ with a value from $Y$, so that the sum of the differences between the two values per pair is as small as possible. So in essence, I suppose I want to minimize the following quantity by rearanging the elements of $X... | 70,544 |
<p>Here is example to workout:</p>
<pre><code>require(lasso2)
data(Prostate)
fit = lm(lpsa~.,data=Prostate)
summary(fit)
lam = seq(0,10000,len=5000)
require(MASS)
ridgefits = lm.ridge(lpsa~.,data=Prostate,lam=lam)
# plot traces for each predictor
plot(range(lam), range(ridgefits$coef),type="n")
clrs <- c("red... | 70,545 |
<p>I have a quadratic regression y against x and I'm interested in the value x where y is the maximum (ymax->x). I can compute x(ymax) but I'm also interested in the standard error or confidence interval of x(ymax) to get x(ymax) +/- standard error or, respectively, lower and upper xmax confidence interval. </p>
<p>O... | 31,573 |
<p>I am trying to compare OLR, ridge and lasso in my situation. I could calculate SE for OLR and lasso but not for ridge. The following is <code>Prostrate</code> data from <code>lasso2</code> package. </p>
<pre><code>require(lasso2)
require(MASS)
data(Prostate)
fit.lm = lm(lpsa~.,data=Prostate)
summary(fit.lm)$coeffi... | 70,546 |
<p>I have data on a dependent variable y and an explanatory one, x, and want to find out if there is a non-linear relationship between theses by running regressions where the data is divided in quartiles from the lowest to the highest value of x. So for example, what is the slope of x when x lies in the first quartile,... | 42,126 |
<p>What is the default significance level for the <code>chisq.test()</code> function in R? I have been trying to figure that one out but couldn't. The documentation seems really poor on these specifications.</p> | 38,012 |
<p>I'm check the residuals of a linear regression with Zivot & Andrews unit root test.</p>
<p>This is the plot:
<img src="http://i.stack.imgur.com/9wK3i.png" alt="enter image description here"></p>
<p>And the results are:</p>
<pre><code>> z <- ur.za(resid(mod), model='intercept')
> summary(z)
#... | 31,580 |
<p>I have run the following logistic regression:</p>
<pre><code>glm(formula = DecisionasReceiver ~ L1 + L2 + L3,
family = binomial("logit"), data = lue)
</code></pre>
<p>where L1 L2 and L3 code for differences in condition of no.GREEN.
L1: 1,-1,0,0 : is there a difference in DecisionasReceiver as no.GREEN changes ... | 70,547 |
<p>I am working on a linear regression problem with Gaussian and sigmoid basis functions. My data set is very large, say a total of 15K inputs with each input having 46 features. I have divided my data into three sets as usual Training, CV and Test. By plotting the ERMS vs Degree of Polynomial for all three sets I chos... | 70,548 |
<p>In the game of poker, how do we test $H_o : \textrm{winrate} > 0$? Or how can we test $H_o : \textrm{winrate} = x$ for $x \in \mathbb{R}$? Winrate might be measured as the population $ profit per hand.</p>
<p>If we think of the average player's profit graph as something like a Wiener process then something that ... | 31,582 |
<p>I am in the process of imputing data (two variables that are 3 point Likert type responses and items of both variables yield multiple subscales). While these variables are ordinal variables, given that they are summed and/or averaged to create subscales, is it appropriate to simply use the SPSS MVA to impute item sc... | 42,129 |
<p>This all pertains to my Psychology honours thesis.</p>
<p>I have two groups (Autism and control) and all participants completed four tasks. It is very important to my study that the groups do not differ on reaction time in each of the tasks. However, they do. The autism group responded faster than the control group... | 70,549 |
<p>I am creating a card game AI for an iPhone game and I'm stumped trying to come up with this statistic.</p>
<p>The deck has 4 suits. The cards are numbered 1-14 in each suit and there is one Joker. So, the deck has 57 cards. One player will be dealt 18 cards and this person will also get to decide which suit the J... | 70,550 |
<p>I have a joint PDF, $P(x,y)$ that is populated, but values of x and y are intermittent and so there is a spike ("delta function") at $P(0,0)$. </p>
<p>If I cut off the delta function (i.e., $P(x,y | x>0 \cap y>0)$ and calculate the covariance from the resulting conditional probability, what would I call it?<... | 70,551 |
<p>Suppose we have a correlated outcome $\mathbf{y}$ and a bunch of predictors $\mathbf{X}$. For some reason, we know the variance/covariance matrix of the error term $(\epsilon)$, say $\mathbf{V}$.</p>
<p>In this scenario, it is reasonable to utilize the <strong>Generalized Least Squares</strong>.</p>
<p>Through Cho... | 31,585 |
<p>Consider the problem of the choice of estimator of $\sigma^2$ based on a random sample of size $n$ from a $N(\mu,\sigma^2)$ distribution. </p>
<p>In undergraduate, we were always taught to use the sample variance</p>
<p>$$\hat{s}^2 = \dfrac{1}{n-1}\sum_{i=1}^{n}\left(X_{i}-\bar{X}\right)^{2}$$ </p>
<p>instead of... | 2,231 |
<p>Let's say a bank has 5 different types of deposits. One type is certificates of deposits (CD), and the other 4 types are different checking and savings account products with various interest rates levels. </p>
<p>The deposit mix represents the sum of the % of deposits allocated to each of the 5 product types. Th... | 37,735 |
<p>My questions is from path analysis.</p>
<p>I have a model with 11 variables (DTPB: Decomposed Theory of Planned Behavior), and I publish questionnaire with likert-scale (1 to 5). Each of this 11 variables have 2, 3 or 4 questions in my questionnaire.</p>
<p>I draw my model in AMOS, but i don`t know how to connect... | 70,552 |
<p>I'm trying to predict the success or failure of students based on some features with a logistic regression model. To improve the performance of the model, I've already thought about splitting up the students into different groups based on obvious differences and building separate models for each group. But I think i... | 39,715 |
<p>I am having difficulties understanding the underlying logic in setting the <a href="http://en.wikipedia.org/wiki/Null_hypothesis">null hypothesis</a>. In this <a href="http://stats.stackexchange.com/questions/12461/how-to-specify-the-null-hypothesis-in-hypothesis-testing">answer</a> the obviously generally accepted ... | 31,593 |
<p>I have a data set of paired measurements $(x_1,y_1),(x_2,y_2),...,(x_n,y_n)$. I need to fit a linear regression line $y=ax+b$ to this data. Therefore, I have to estimate the parameters $a$ and $b$.</p>
<p>How can I then calculate the confidence interval for these estimated parameters?</p>
<p>I referred to the wiki... | 49,619 |
<p>I am trying to compute the entropy for different sets of data and then compare the obtained values.</p>
<p>The idea is that the sets of data may change their size, I might have sets sizes ranging from 10 to 200 values.</p>
<p>In order to compare the entropy level obtained for them should I first normalize it with ... | 70,553 |
<p><strong>Question</strong>: How can I construct a test to determine if the observed "mountain"-allele frequency (Fig 1) is significantly lower in the central to southern mountains than predicted (Fig 2) by the ecological selection model (<em>see below for details</em>)? </p>
<p><strong>Problem</strong>: My initial t... | 31,595 |
<p>Here is a recent Google correlate query:<br>
<a href="http://www.google.com/trends/correlate/search?e=internet+usage&t=weekly#" rel="nofollow">http://www.google.com/trends/correlate/search?e=internet+usage&t=weekly#</a></p>
<p>As you can see in the search box at that link, I entered "internet usage" and Goo... | 70,554 |
<p>I've got a causal inference situation with heterogeneous treatment effects. In addition to simply estimating coefficients, I'd like to get an average effect of the treatment at the covariate values that I observed in my dataset. For example:
$$
y = \alpha+\beta_1 T + \beta_2Z + \beta_3 (T\times Z) + X'\gamma + \ep... | 28,686 |
<p>I have a model where categorical (mutually exclusive) variables predict bankruptcy. Chi-square is significant. How can I code a logistic regression model in <code>MATLAB</code> that proves that some of these variables explain the bankruptcies better.</p>
<p>There are 4 variables: which implies 3 dummy variables.</p... | 31,600 |
<p>We've created a survey asking students, among other things, their GPA (=weighted average of grades) and their marks in some specific courses (which count towards GPA).</p>
<p>We wanted to see which regressors influence the GPA using a simple OLS model. <strong>Is it sensible to use a formula like this?</strong></p>... | 42,140 |
<p>According to the <a href="http://en.wikipedia.org/wiki/Point-biserial_correlation_coefficient" rel="nofollow">wikipedia article</a> the point-biserial correlation is just Pearson correlation where one variable is continuous but the other is dichotomous (e.g. Yes/No, Male/Female). However the article later introduces... | 70,555 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/11113/wrong-results-using-anova-with-repeated-measures">Wrong results using ANOVA with repeated measures</a> </p>
</blockquote>
<p>Hello everybody,
I did an experiment and I need to understand how to detec... | 49,851 |
<p>Suppose we have a set $S$ consisting of $p$ features, and a subset $S_+$ of the features are positive. If $Q$ is any subset of $S$, define the false positive rate as the proportion of features in $Q$ which are not positive:</p>
<p>$$FPR[Q] = 1 - \frac{|Q \cap S_+|}{|Q|}$$</p>
<p>where $|\cdot|$ denotes cardinalit... | 70,556 |
<p>I am running a model for a problem in insurance domain. The final results show some false positive x and some false negative y. I am using SAS Enterprise Miner for this. Can somebody suggest me how to reduce false positive? I know for this i have to increase the false negative. I want to know two things: </p>
<ol>... | 70,557 |
<p>Suppose we want to test whether $Z$ is a confounding variable for the effect of $X$ on $Y$. Is it enough to just check unadjusted and adjusted estimates of the coefficient of $X$ and see if they differ? Also, if the difference between the two is very small (e.g $1/1000$) can we say that there is no confounding? It s... | 49,307 |
<p>In R, how do I specify lmer model without global fixed effect? For example, if I say something like</p>
<pre><code>lmer(y ~ (1 | group) + (0 + x | group), data = my_df)
</code></pre>
<p>the fitted model will be</p>
<p>$y_{ij} = a + \alpha_{i} + \beta_{i} x_{ij}$</p>
<p>How do I fit model</p>
<p>$y_{ij} = \alpha... | 70,558 |
<p>I had a question on calcuating James-Stein Shrinkage factor in the <a href="http://www-stat.stanford.edu/~ckirby/brad/other/Article1977.pdf">1977 Scientific American paper by Bradley Efron and Carl Morris</a>. </p>
<p>I gathered the data for the baseball players and it is given below:</p>
<pre><code>Name, avg45, a... | 70,559 |
<p>I'm new here and wondering if anyone could give me some hints on how to estimate the time varying coefficient and state variable together. Here is my model:</p>
<p>observation equation: $Y(t)= A(t)X(t)+ w(t)$,<br>
state equation: $X(t)=\phi X(t-1)+v(t)$, </p>
<p>here I have time varying coefficient $A(t)$, it does... | 70,560 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.