62k views

### What is the difference between McNemar's test and the chi-squared test, and how do you know when to use each?

I have tried reading up on different sources, but I am still not clear what test would be the appropriate in my case. There are three different questions I am asking about my dataset: The subjects ...
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19k views

### Comparing and contrasting, p-values, significance levels and type I error

I was wondering if anybody could give a concise rundown as to the definitions and uses of p-values, significance level and type I error. I understand that p-values are defined as "the probability of ...
• 1,505
19k views

### Why use a z test rather than a t test with proportional data?

When testing the difference between 2 proportions why do we use a z-test rather than a t-test? Further, is there a simple way to conduct an omnibus test for significant differences between more ...
• 265
5k 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 ...
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4k views

### Is the beta distribution really better than the normal distribution for testing the difference of two proportions?

I'm working at an online agency, where we run a lot of AB testing in order to test differences in proportion between two groups (test vs. control). Standard practice in the industry for testing ...
2k views

### Interpretation of p-value in comparing proportions between two small groups in R

I wish to compare proportions between two small groups. In group 1, 2 of 18 students received honours. In group 2, 9 of 21 received honours. This is a small sample, so if I use the t-test: ...
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1 vote
4k views

### How to test for significance if groups differed at baseline?

I have a situation where I want to test for a statistically significant difference in the percentage of customers who own a product among two groups. The treated group gets a marketing message, and ...
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2k views

### T Test or Chi Square?

There are 2 variables, City and No Of Matches won. Variables: 1City Sydney Canberra 2No Of Matches Won? Sydney: 200 out of 300 Canberra: 210 out of 300 Question: Is team Canberra ...
1 vote
328 views

### $\chi^2$ test of significance vs. goodness of fit

I have 644 companies out of which 154 went bankrupt. I investigate below if the bankruptcy is related to the sector type: ...
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