Linked Questions

8
votes
1answer
3k views

chi squared test or Z test? [duplicate]

I have an outcome from a biological experiment, where I have counted the number of dead cells upon a mutation. For example, in once case - out of 120 cells we saw 16% of the dead cells, but our ...
4
votes
1answer
449 views

Test of proportions or chi-squared? [duplicate]

These data are from an A/B test of free trials to conversion. Someone can sign up for a 30 day free trial of the product. If they like it they stay on and become paying customers. By default (A), when ...
15
votes
1answer
2k views

At What Level is a $\chi^2$ test Mathematically Identical to a $z$-test of Proportions?

BACKGROUND: Skip safely - it's here for reference, and to legitimize the question. The opening of this paper reads: "Karl Pearson’s famous chi-square contingency test is derived from another ...
4
votes
0answers
4k views

Assessing A/B test results using Python

Problem's setting Assume having results of an A/B test. You let you users experience two variants of your website and you counted how many converted: ...
2
votes
1answer
530 views

Difference estimate & confidence intervals for $\chi^2$ test between 2 proportions

I am using a chi-sq test between two proportions (http://statistic-on-air.blogspot.com/2009/07/comparison-of-two-proportions.html). I am using this over the z-test for proportions because I do not ...
1
vote
1answer
272 views

Can I use a two proportion z-test?

I have a response, "Satisfaction" that goes on a scale from 0-10 (where 0=dissatisfied and 10= very satisfied), and I have a predictor variable that also uses the same scale. I recoded the response so ...
1
vote
0answers
292 views

Appropriate Correction for 2 proportion test? --with example--

Below is an example of frequency data between observed and expected proportions. Can I simply run a 2-Proportion z test here? Or, would I be violating assumptions? If I were to run dozens of z tests (...
0
votes
1answer
157 views

Appropriate test for proportion data

I have two independent groups A and B. Each participant is given 5 questions to solve and his/her answer is evaluated as correct or incorrect. However, participants can skip questions, so the number ...
0
votes
0answers
172 views

Confusion about z-test and chi square test on a very basic example

I am confused with the difference between z-test and chi square test. In book Agresti 2007 An introduction to categorical data analysis, page 9, the author had an example of testing Do a majority ...
1
vote
1answer
144 views

What statistical test do I use for differences in proportions?

I have two groups of samples with a proportion of mutations in each sample being a particular type (the proportions are represented as a fraction of 1). How to I check if that type of mutation is ...
2
votes
1answer
109 views

How to process Binomial-Binomial data on SPSS for hypothesis testing?

There are 2 groups of 100 pregnant women: the first are malnourished and the second are well-nourished. A COHORT research is being done on them to determine if malnutrition is a risk factor for low ...
3
votes
0answers
48 views

When to use Chi-squared and when Z test for categorical variables?

The problem is: There was a survey conducted among 1137 adults from California, Nevada, and Oregon. They were chosen randomly and they answered to the following question “Do you think Marijuana ...
1
vote
1answer
36 views

What statistical test do I need to see if there is a statistical significant result?

I have demographic data for a specific group of students. I then have the demographic data for a subset of these students who have failed their courses. How to I test whether or not particular ...