Linked Questions

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0answers
2k views

Sample size for logistic regression with categorical independent variables [duplicate]

Trying to find a sample size for logistic regression I found a rule of thumb in http://www.medcalc.org/manual/logistic_regression.php I cite: Sample size considerations. Sample size calculation for ...
1
vote
0answers
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?
3
votes
2answers
169 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 ...
0
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0answers
343 views

Sample size for logistic regression. How to determine the number need for positive and negative cases? [duplicate]

I would like to apply logistic regression for my research. And before that, I want to calculate the minimum number of sample size, positive cases, and negative cases. http://www.medcalc.org/manual/...
0
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1answer
203 views

Need help determining sample size for logistic regression [duplicate]

I need help determining the sample size necessary for a logistic regression (binary DV) with two continuous predictors and also the sample size necessary if I use three continuous predictors.
0
votes
1answer
117 views

Is there a relationship between number of covariates and sample size in logistic regression? [duplicate]

Is there some definite relationship between number of covariates and the sample size in logistic regression? (e.g. larger the number of covariates, larger the sample size needed, etc.) Thank you,
1
vote
0answers
156 views

Why exactly is a sample of size 142 too small for 11 variables? [duplicate]

In a (logistic?) regression paper related to credit scoring and involving psychometric data and credit scoring, there are 11 predictor variables used to estimate credit score. The sample size is 142. ...
0
votes
1answer
116 views

What is the minimum number of “cases” for minority class to perform logistic regression? [duplicate]

I have 6 out of 167 cases of cancer in the dependent variable. I would evaluate if three independent variables predicted the cancer. Are 6 cases enough? Is there a rule to determine this? Is there ...
0
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0answers
20 views

Sample size in logistic regression [duplicate]

When talking about minimum sample size for logistic regression, do they mean the total number of observations in the study, or do they mean number of observations in the categories you are ...
0
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0answers
20 views

Can I work around a small number of samples in a logistic regression? [duplicate]

I am deeply frustrated, I have a dataframe with a small number of samples (N=13) and am trying to do a logistic regression with binomial variables. I know, that especially given that there is an even ...
163
votes
8answers
153k views

How to deal with perfect separation in logistic regression?

If you have a variable which perfectly separates zeroes and ones in target variable, R will yield the following "perfect or quasi perfect separation" warning message: ...
81
votes
3answers
71k views

Does an unbalanced sample matter when doing logistic regression?

Okay, so I think I have a decent enough sample, taking into account the 20:1 rule of thumb: a fairly large sample (N=374) for a total of 7 candidate predictor variables. My problem is the following: ...
8
votes
4answers
24k views

Minimum number of observations for logistic regression?

I'm running a binary logistic regressions with 3 numerical variables. I'm suppressing the intercept in my models as the probability should be zero if all input variables are zero. What's minimal ...
4
votes
3answers
5k views

Multiple logistic regression power analysis

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 ...
6
votes
1answer
4k views

Power calculations, logistic regression with continuous exposure--cohort [duplicate]

I'm trying to estimate power in a logistic regression with a continuous exposure in a cohort study (ie, the ratio of the sampling probabilities is 1). I have population cumulative incidence (...

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