# All Questions

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### Is my random variable affecting my response?

I performed an experiment on coral colonies (10 colonies, randomly chosen in repeated measurements); manipulating aragonite/carbon chemistry and temperature (fixed effect) to analyse effects on the ...
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Okay, this might seem like a stupid question and it sure feels that way. And I have probably just lost myself by overthinking it or something, but here goes: In Cohrans C-test you take the ratio ...
13 views

### 3x2x3 ANOVA with repeated measures

I am a beginner of statistical analysis. Currently I am using SPSS software statistical package. How to perform repeated measures ANOVA for the following data: 5 emotional states x 2 hemispheres x 5 ...
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### Estimating the disequilibrium error in ECM

I am supposed to estimate the labour market disequilibrium for my master thesis. I am using an error correction model specification for the federal states in Germany. I am using labour (emp), gdp, ...
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### marginal effect clogit not significant

I developed a coniditional logit model on STATA, the model is good and the variables are highly significant Then I do mfx predicted (PU0) to determine the marginal effects of variables (dy / dx). the ...
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### When does replication reveal fraud?

Found this question here, and I couldn't answser it and thought it would be a wonderful question for this site. Here's a little thought experiment for your weekend pleasure. Consider the ...
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### How do I analyse a two-alternative forced choice test?

I have recently as part of my bachelor project at my university conducted a two-alternative forced choice test. I have looked at ways to say something with significance about which images (the test ...
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### Probability distributions

What is the probability that a random number [0,1) will lie in [0.5,0.6]? As far as I know, there are 3 probability distributions in physics we usually use, but I am not sure when we can use ...
39 views

### How does SVM prediction work?

As far as I understand, the training phase usually uses the dual optimization formulation where we can implicitly calculate the weight vector which defines the discriminant function. How about the ...
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### Simple mean reversion measure for binary time series

I am trying to define a simple measure for mean reversion in a stochastic sequence of ones and zeros, which I denote by $x_t$. Yes, a unit root test on the cumulative sum could be a viable choice, ...
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### What is endogeneity and what does it mean substantively? As an extension what is exogeneity?

My apologies if this is an obtuse question, I am neither a statistician nor a econometrician but as a student is empirical methods this question plagues me. I understand that $$X'\epsilon=0$$ not ...
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### How to score the options in a questionnaire and develop a scoring range in a risk profiler questionnaire?

I have developed a risk profiler questionnaire but don't know how to score the options and make a scoring range. Once the range is developed, I could categorize the client as conservative, moderate ...
46 views

### Simulating multiple linear regression

I would like to simulate a multiple linear regression model using R. If I have the skewness and kurtosis for the residuals, how can I do that?
68 views

### Why are log transforms used in measuring dose-time association?

Explain why log(dose) and log(time) are used to measure the association between dose and time instead of the actual values of dose and time.
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### Dummy coding for contrasts: 0,1 vs. 1,-1

I'm seeking your help in understanding the difference between two different contrasts for dichotomous variables. On this page: http://www.psychstat.missouristate.edu/multibook/mlt08.htm under ...
59 views

### Finding Abnormally Low Ticket Prices

I'm creating a program where my goal is to analyse lists of ticket prices and locate tickets that are priced abnormally low in relation to the spread of prices. My preliminary model does the ...
43 views

### Independent, Dependent Variables, Nonlinear

So, I am not a statistician, but a burgeoning mathematician. Here is something that is perplexing me in statistics, however. My apologies if the question is silly, on one hand, or just not solvable, ...
46 views

### How to construct a 95% Confidence Ellipse in R [closed]

See the cross-post at http://stackoverflow.com/questions/16659749/getting-the-ellipse-function-to-match-the-dataellipse-function-in-r. So I am sampling from a multivariate normal distribution in R, ...
92 views

### Overfitting when using corrected AIC for model selection

I am using the corrected AIC to select the lag order in a simple AR(p) model. I chose the the AICc since my sample is fairly small (n=135). The AICc minimal model is the AR(15). To me it seems like an ...
73 views

### Why do I get same results for OLS and GLS in R?

When I run this code: ...
85 views

### Is there a general definition of the effect size?

The effect-size tag has no wiki. The wikipedia page about the effect size does not provide a precise general definition. And I have never seen a general definition ...
28 views

### Statistical Distance Within Multivariate Distribution

Suppose you have some multivariate normal distribution $X \sim N(\mu,\Sigma)$. Is there a good way to calculate a measure of distance between an arbitrary $X_{i}$ and $X_{j}$ of $X$ (I suppose the ...
105 views

### Is the exponential distribution a good model for this data?

I'm trying to determine if the exponential distribution is a good model for a data set that I'm exploring. It doesn't have to be precise. I'm using the data for capacity planning (if it's a good fit) ...
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### OK to use residual sum of squares for cross-validation of binary outcome?

For an OLS model the mean squared error can be used to assess the fit of the trained model on the validation data. What is the equivalent for a logistic regression model? Can I simply use the ...
30 views

### Standard errors of regression coefficients based on sample size

For any particular nonlinear regression: $$Y_i = f(\mathbb{x_i},\theta) + \epsilon_i, i=1,...,n$$ I currently have standard errors for each of the $\theta_j$ obtained via the Gauss-Newton algorithm ...
30 views

### Which variables are driving correlations within groups

I'm running an analysis on a few data sets that each typically have 100-200 cases measured across 120-160 variables - something similar to looking at gene expressions. Each variable is a non-centered ...
40 views

### Why do R function eigen()' and Armadillo's eig_sym()` give different results

I am trying to compute eigenvalues in C++ using the Armadillo function eig_sym via RcppArmadillo. The results are not entirely ...
17 views

### Confusion related to regularization parameter selection by cross validation

I can see lots of paper mentioning they selected some parameters like regularization parameter $\lambda$ by cross validation. What do they mean by that?
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### Repeated Measures in R, SAS or SPSS: Whale Body Temperature Data

I have a question regarding a repeated measures experiment. I have 5 whales (randomly selected) that I recorded body temperature on. Data was collected via satellite, programmed to transmit records at ...
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### neuralnet error

I am trying to train neuralnet model by using caret package by this command: ...