illustrates the effect of sample size on the power of a two-sample t test?
illustrates the effect of
A test of hypothesis consists of 2 hypotheses: the null, H0, and the alternative, H1.
For a sample t test of the mean, the null hypothesis H0 is a simple statement about the value the difference in the means is expected to have.
Power:
The power of the test is the probability of correctly rejecting the null, H0, when the alternative H1 is true in reality.
The power is the probability of “true negative”, that is, the probability of a “negative decision” (decision: null hypothesis is true), when it is really negative (real situation: null hypothesis is negative).
The power also determines how specific or accurate the test is, in detecting the alternative hypothesis when the alternative is true.
Six ways to increase the power for the study:
- Increasing effect size by increasing difference between the known population and predicted population means.
- Increasing effect size by reducing the standard deviation of population.
- Increasing size of the sample.
- Using less extreme or more lenient value of significance level.
- Using one-tailed for the result of the predicted distribution.
- Using more sensitive hypothesis-testing procedure.
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