# All Questions

18 views

### Device Comparision: Correlated or uncorrelated measurements

Background: I want to compare two devices measuring a certain characteristic on a subject. Thereto, each subject is measured once with device A and once with device B. It needs to be assumed that ...
9 views

### How to test the significance of covariance?

I'm using the Mutual Informacion covariance in RNA sequences and I want to know if there exits a way to test if some covariance is significant, let's say, an associated p-value. Thanks to all for ...
25 views

### Let's talk sales forecasts - integrating a time series model with subjective “predictions/ leads” from sales team

I've learned a lot about time series forecasting this previous year, but one thing that's still a bit lacking in terms of a formal system is integrating a future sales projection into an existing time ...
212 views

### Why doesn't my Wiener process simulation work?

The Wiener process at time $t=0$ is $0$. It has independent increments, so $W_t-W_0 \sim N(0,t-0)$, but wouldn't it mean that $W_t\sim N(0,t)$ for every $t$? But if I try to simulate a a ...
12 views

### How do I fit a linear mixed model in R with autocorrelation, when the effect of time is of no interest?

I am attempting to fit a linear mixed model with the lme function using R. My data involve repeated measures, but the effect of time is not of interest to me, so I don't want to include it as a fixed ...
4 views

### Best procedure for evaluating group differences in a Lasso regularized regression

I am evaluating 25 predictors (continuous, ordinal, multinomial) on an ordinal outcome variable using a lasso regularized regression. I am using the lasso for variable selection, to determine which ...
19 views

### Nonparametric Sampling with Correlation

I have two random variables, $X$ and $Y$. They represent real, physical entities. And in reality, $X$ "feeds" $Y$ (imagine a physical process where $X$ and $Y$ model some uncertain phenomenon, but the ...
17 views

### Robust OLS standard errors (Newey-West)

I am running a simple OLS regression with HAC adjustment (i.e. Heteroschedasticity and Autocorrelation adjustment) using the following function in hac() in matlab. ...
9 views

### Normality for Confirmatory analysis with Likert scale data

I'm running CFA on AMOS for an attitude scale and I got a good model fit after deleting three problematic items (less than .30 factor loadings). However, my data is not normally distributed. I was ...
21 views

### Can I use likelihood-ratio test to compare two samples drawn from power-law distributions?

I have to compare two large samples ($N = 10^{6}$) of discrete data drawn from power-law distributions to assess whether they are significantly different. I can't do that by means of ...
13 views

### maximizing matrix diagonal elements in R [migrated]

Given a matrix (or table in R ) ...
34 views

### How to make a statistic? [on hold]

I am a student and want to study statistics. I have started little with making random diagrams or statistic about random stuff but now a problem have occurred. The problem: My teacher gave me a site ...
7 views

### Literature on a specific identification strategy (DiD)

In part of an econometric project I need to run a specific DiD. Yet I can't find specific literature related to it. I'm sure it exists similar things but I have difficulties. Maybe you could help me ...
6 views

### Sub-space / latent-space covariance

I am not entirely sure what I should be googling for this in my present context. Basically I am working with a set of latent variable models such as the Gaussian Processes latent variable model ...
7 views

### How to make a confusion matrix from comparing prediction results of two algorithms?

I applied two unsupervised algorithms to the same data, and would like to make a confusion matrix out of results, how should I achieve it in R? An example with R codes like following: ...
14 views

### Temporal correlation [on hold]

I have three events, temporal happpening in t1, t2 and t3. I have a master event, that happens in t0. Being ...
6 views

### Need for correction of persp plot?

I have problem with persp and contour plot to visualize PDF and CDF plot of bivariate standard normal plots in R. When I call the generic function persp() and contour() I got wrong plots of PDF and ...
8 views

### T-test degrees of freedom

I have just been creating a slide demonstrating a (central interval) confidence band plot using a Neyman construction for a simple standard normal distribution. I created a confidence band plot of ...
12 views

### Median absolute deviation: impact/bias when forcing a median of zero

I want to estimate the median absolute deviation (MAD) of a signal. The MAD is defined as the median of the absolute difference between the signal and its median. Now I have a signal that I know for ...
9 views

### When can one use Hochberg's or Hommel's method for adjusting P values?

The p.adjust function in R can produce P value adjustments based on methods from Hochberg and Hommel, which are both more powerful than methods from Bonferroni and ...
203 views

### Why Multiple Linear Regression cannot be built when p>n?

My question is why Multiple Linear Regression (MLR), based on least squares, cannot be built when the number of variables $(p)$ are larger than the number of samples $(n)$? Can one explain why is it ...
29 views

### what is the differences between LDA and MLR? [duplicate]

I know that Linear Discrimination Analysis (LDA) is used for classification and Multiple Linear Regression (MLR) is for regression. Lets say I have a matrix X (independent variables) and Y(dependent ...
8 views

### Covariance function to draw an inverse function

In a Gaussian Process (GP), we know that choice of the covariance function determines the shape of function that can be drawn from the GP. eg. Constant : $\sigma _{o}^{2}$ Draws constant function ...
19 views

### How to find original features corresponding to the first two principal components? [duplicate]

I have a set of data described by $n$ features. I do a principal component analysis (PCA) to reduce it to just 2 dimensions so I can make a 2D plot of the data, with the first two Principal ...
12 views

### can I fix one variable in SAS 'estimate'? [migrated]

In sas "Proc mixed" procedure, can I use 'estimate' for one variable fixed? for example ...
9 views

### finding weights of aspects

I have aspects(nouns) from online customer reviews of a product. I have done sentimental analysis to get polarity of each aspect. Now I want to weight the ...
5 views

### Which Latin Square Design

I am to design a clinical trial about finding the effects of some pressure on a vein's cross sectional area. There 3 levels of pressure 0,5,10 and two groups of people are considered obese and normal. ...
21 views

### Which program for PVAR? [on hold]

I have been looking at some studies that use panel vector autoregression models. The problem is, I can't find which statistical package the authors use. I would like to estimate impulse responses in ...
13 views

### Technical Indicators reference [migrated]

I have been looking for a good reference where I can find how technical indicators of stock market analysis are calculated. I have a dataset (time series) which I want to extract these indicators to ...
7 views

### Fisher's exact test for 3x5 contingency table in R with post-hoc? Consistently with using Fisher or Chi-squared?

I'm struggling with some (relatively simple) stats questions for some work I'm doing in R, and can't seem to find answers online... I have a factorial response variable of habitat type of a species ...
34 views

### Significant turning points in fractional polynomials

When using fractional polynomial models it has been suggested to use the first derivative of the polynomial function to identify significant periods of change and the second derivative to identify ...
18 views

### Costs in a game [on hold]

I am trying to find the best model to solve the following problem: I have various players in a network. I have to visit all these players in the network. The players are visited in an optimal route, ...
10 views

### Hetoroskedasticity changes with similar dependent variables

I have two regressions with the same "independent variables" . The "dependent" variables is a ratio where what changes is the denominator. In other words, the two dependent variables have the same ...
4 views

### Response surface models using quantitative variables

This relates to the mineral industry so a little context first. We are trying to estimate the uncertainty in the amount of ore that can be recovered from an ore body mine. This depends on things ...
3 views

### R Packages for rank-preserving structural failure time model (RPSTM)

I have a randomized clinical trial data that has high percentage(30-40% in both arms) switching over to a different treatment regimen. By browsing through some literature, I am inclined to perform ...
26 views

### How to emphasize on specific data points in Linear Regression?

I'm now solving linear regression problems. $y = wx + b + e$ So I have $(x, y)$ data set and want to learn weights $w, b$. Additionally I know that certain data points are not polluted by noise ...
10 views

### Examining Validity and Reliability of a new questionnaire (Likert scale)

I need to examine the psychometric properties of a newly developed questionnaire. There are 22 items with a 5-point Likert Scale. The designed questionnaire includes two main scales. How do I ...
17 views

### How to do pooled logistic regression in Stata? [on hold]

How do you go about doing pooled logistic regression in Stata? Can't find any info online!
14 views

### Create a histogram with mean and stddev

I have such a set of data to create a histogram in frontend. ...
36 views

### Basic methods for detecting outliers

Let $X$ be a matrix of $n$ rows and $m$ columns. $n$ is the number of samples and $m$ is the number of gene expressions. Gene expressions are basically numerical continuous values. Assume we have a ...
10 views

### Estimating the false discovery rate under the F-test statistics

We have food as a factor that can take in 3 values and 2 test scores as dependent variables. Basically, there are $k$ students who consume one of these food types before taking both tests. We want to ...
8 views

### Statistics question regarding sample size and test statistic [on hold]

Does Increasing the sample size makes the standard error smaller which in turn makes the test statistic larger (more extreme)?
14 views

### Analyzing Social Behavior in Bats

I had a question about what might be the best way to approach one of my datasets. I had been using one method, but a recent talk with one of my professors made me think that perhaps it wasn't the best ...
17 views

### On conditional/joint probability [duplicate]

Problem 1 The table on the left shows the joint probability distribution between two random variables - X and Y; and the table on the right shows the joint probability distribution between two random ...
15 views

### How to prove that Radial Basis Function can be derived by mapping function?

How to prove the radial basis function $k(u,v) = \int_{\mathbb{R}^d} \phi_t(u)\phi_t(v)dt$ can be integrated out by mapping function? \phi_{t}(u) = \frac{1}{(2\pi\Sigma)^{d/2}} ...
6 views

### Effect of 4 options on one column of variables

Column 1 Column 2 1 56 3 18 3 27 2 31 4 22 1 32 2 65 4 39 How do I find out how much a 1,2,3 or 4 ...
16 views

### Is the significance of difference in slopes equivalent to the significance of the slope of the difference of two series?

Say you have an independent variable, $x$, and two dependent variables $y_1$ and $y_2$. I want to calculate whether these two variables have a significantly different slope. I can do it by calculating ...
11 views

### pair-wise comparison for two sets of data where each point contains multiple values

I have two sets of data of the same subjects with 8 time points in each set.The second set is a repeated measure of the same 5 subjects. There are 5 subjects polled per time point. Is it correct to do ...