677 views

### Power Analysis for Logistic Regression with one nominal variable [duplicate]

How do I estimate sample size or do power analysis for logistic regression with one nominal independent variable? Is there a way to do it with Stata?
174 views

### Power analysis for logistic regression with dummy independent variables [duplicate]

Per reviewer request, I need to do power analysis for a logistic regression model with multiple dummy variables. I have four groups: Control, (Treatment) A, B, and C. The hypothesis is that group A ...
177 views

### Power analysis for logistic regression [duplicate]

I have to deliver a statistical analysis plan that will have to be approved by an ethic commettee before I could start a clinical trial. I usually deal with different kinds of tests, whose power ...
90 views

### Power analyses of 5 populations of infection data (binomial data) [duplicate]

I am PhD Biologist. I have 5 populations of infected moth larvae (3 inbred, and 2 outbred). The infection in this case is spread vertically (from mother or father to offspring). Normally the virus is ...
287k views

### Difference between logit and probit models

What is the difference between Logit and Probit model? I'm more interested here in knowing when to use logistic regression, and when to use Probit. If there is any literature which defines it using ...
37k views

### Significance contradiction in linear regression: significant t-test for a coefficient vs non-significant overall F-statistic

I'm fitting a multiple linear regression model between 4 categorical variables (with 4 levels each) and a numerical output. My dataset has 43 observations. Regression gives me the following $p$-...
16k views

### Calculating statistical power

As I understand it, I need to know at least three aspects (out of four) of my proposed study in order to conduct power analysis, namely: type of test - I intend to use Pearson's r and ANCOVA/...
7k views

### Power analysis for ordinal logistic regression

I am looking for a program (in R or SAS or standalone, if free or low cost) that will do power analysis for ordinal logistic regression.
64k views

### How can a regression be significant yet all predictors be non-significant? [duplicate]

My multiple regression analysis model has a statistically significant F value however all beta values are statistically non-significant. All the regression assumptions are met. No multicollinearity ...
3k views

### Experiment or simulation to undestand type I and type II errors

I am studying Type I and Type II errors and basic concepts of testing hypotheses. To better develop my intuition I would like to write a few simple simulations. What I'm hoping is to get a base ...
14k views

### Sample size and power calculations for a randomized controlled trial

I need help with the power calculations to determine the sample size of a randomized clinical trial. This is a relatively simple trial with two arms: an intervention arm and a control arm. Patients in ...
945 views

### Power for experimental design

It's easy to calculate power for paired t-tests and ANOVA, but how do you calculate power for more complicated designs such as split plot designs or factorial designs?
4k views

### Computing the power of Fisher's exact test in R

Suppose that I have the following 3 x 3 contingency table: ...
I have a logistic regression model and output an $R^2$ value. I then go and add another predictor variable to fit a second model. I can output a new $R^2$ value associated with the second model. When ...