# Binary Logistic regression results

Is it correct to find that an explanatory variable was found to be statistically significant with the chi-square test but insignificant with the logistic regression analysis model?

• Does your logistic regression model only have one explanatory variable in it? – user95564 Nov 19 '15 at 19:04
• No it has several explanatory variables,about 10 of them. – Etta Nov 19 '15 at 19:19
• It sounds as if you are running the risk of double dipping. You can't use associations with $Y$ to decide which variables to test for associations with $Y$. Besides that, adjusted and unadjusted (for covariates) analyses naturally differ. – Frank Harrell Nov 19 '15 at 19:27
• Does this mean that the results might be faulty or the approach wrong? – Etta Nov 19 '15 at 19:45
• Correct. Look at some of the rules of thumb for the required sample size as a function of the number of candidate predictors, and pre-specify a full model and use it as the basis for your conclusions. – Frank Harrell Nov 19 '15 at 21:23