# Tag Info

## New answers tagged statistical-power

1 vote

### Determination of sample size vs. repeated measurements in experimental design

I want to compare the performance of two versions of a widget using a 2-sample comparison test. H_0 = both versions perform the same, H_1 = widget.b performs worse than widget.a. Your hypotheses ...
• 1,425
Accepted

### Power of two-sample z-test

Your formula is for a one-sample test, that is for testing the null hypothesis that the mean of a population has a given value given a single sample from it. You can check the 'one sample' calculation ...
• 2,044
Accepted

### How to calculate sample size from hazard ratio?

The key reference here is Schoenfeld (1983), who gives the following formula: $$\frac{(z_{1-\beta}+z_{1-\alpha})^2}{pA\times pB\times\text{log}(\text{HR})^2}$$ This will give you the number of ...
• 3,658

### Determination of sample size vs. repeated measurements in experimental design

Repeated testing of one widget will allow you to determine the magnitude of measurement variation (noise) and, maybe, if there are time or test-dependent changes in the performance. Those things are ...
• 14.9k

### Should we favor family-wise error rate control or statistical power?

Type I errors (false positives) should be protected against where they are more costly than type II errors (false negatives). There are many context-dependent factors that need to go into ...
• 14.9k
Accepted

### Calculate sample size in an experiment with interactions

This looks like a two-way ANOVA disguised as a three-way ANOVA. The critical things I see that you are testing are these two factors: The effect of stimulation. The effect of treatment. (Optional) ...

### How can power and effect size help me interpret my A/B test results?

I'll take an unpopular but correct stance. If you want to 'interpret' or understand, or do anything else beyond an automatic decision that would be relevant to acceptance testing of widgets, you ...
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### How can power and effect size help me interpret my A/B test results?

Surely, they can help me interpret the results of my test, one way or another? Power is something computed conditional on some assumption about the true effect size. If the effect size was at least ...
• 35.2k
Accepted

### How can power and effect size help me interpret my A/B test results?

Power and effect size together tell you the probability that you'll correctly find a significant result, if the true effect really is as large as the effect size. You've correctly noted that the p-...
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### How can power and effect size help me interpret my A/B test results?

You wrote I could arbitrarily increase or decrease both power and effect size (and keep contant n) No, this is incorrect, unless no one else will look at your analysis. It's true that if you set a ...
• 117k