Covariates in a case control study

I am doing a retrospective analysis on a study has has cases and controls. I am looking to see if there is an association with death, using exact logistic regression. I am confused on whether I need to include covariates in the model that are associated with the outcome (death) or the independent variable of … Read more

Centrality measures and interpretation

I am new to graph theory and I have some questioning. First of all, how can I determine the significant of two different degree centrality means and two different closeness centrality means? For example, I have a network of international organizations which are public or private, but I don’t know how to determine if the … Read more

Stratified Paired T-Test for One Group

I have pre/post data where all subjects underwent the intervention. The outcome is a score. I am also looking to stratify my analysis by gender. I understand I can stratify my paired t-test in SAS via a simple class statement, but how do I determine if the difference between the genders are significant? I would … Read more

How do I test for differences in cost per acquisition (CPA) in an A/B test?

How would I go about testing for differences in cost per acquisition (CPA) in an A/B test? I’m a huge novice and am unsure if I would use some kind of t-test or chi-square test (or neither) to compare the proportion of cost per acquisition in group A to cost per acquisition in group B. … Read more

Testing for a significant difference between 2 groups

Question 1 Two equally sized patches of the night sky are examined: Patch A contains 100 stars Patch B contains 110 stars Is there a significant difference between these two patches of night sky? i.e., is one patch likely to contain a star cluster? Question 2 Traffic to a site is examined in two time … Read more

Run multiple T-test and correct for multiple comparisons [closed]

Closed. This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 2 years ago. Improve this question I have tried to look for a quick way to solve this questions but I have found no complete solution … Read more

How to test hypothesis of no group differences?

Imagine you have a study with two groups (e.g., males and females) looking at a numeric dependent variable (e.g., intelligence test scores) and you have the hypothesis that there are no group differences. Question: What is a good way to test whether there are no group differences? How would you determine the sample size needed … Read more

Effectiveness of exam: did it achieve the goal?

I have a dataset of student scores in an exam. Its structure is as follows: Group Subgroup StudentID Score(4 Categories) AssessmentDate 001 001 00001 1 20170401 001 002 00002 2 20170401 There are nearly 10000 students, divided into 10 groups, each having 20 subgroups or so. Different raters were assigned to groups or subgroups, so … Read more