Exam 2 Review - Chapter 8 Flashcards
What is a point estimate?
A single number used as an estimate for a population parameter. (A mean, for example)
What is an interval estimate?
A range of possible values for the population parameter.
What does a 95% confidence interval mean?
It means that 95% of the time, the population mean will be included in an interval mean (assuming that the sample size stays the same).
How do you find a 95% confidence interval?
To find the lower and upper ends, add or subtract 1.96 multiplied by the standard error from the sample mean.
Why is it a good thing to use confidence intervals?
More information is provided than the classic null hypothesis test.
What is an effect size?
The size of a difference that is unaffected by the sample size. (How big is the difference? Is it meaningful?)
How do you find Cohen’s d?
(sample mean - population mean)/standard deviation
What does Cohen’s d mean?
- 0.8 = large effect size
- 0.5 = medium effect size
- 0.2 = small effect size
What is statistical power?
A measure of the likelihood that we will reject the null hypothesis, given that the null hypothesis is false.
What affects statistical power?
VAMOS - Variability (decrease it), Alpha (increase it), Mean differences between populations (increase it), One tailed tests, and sample size (increase it).
How is power calculated?
Determine the critical value, then subtract the sample mean from it before dividing by the standard error.
How is the critical value for a statistical test found?
z(standard error) + mean of population
What is a meta-analysis?
A study or method that involves the calculation of a mean effect size from the individual effect sizes of many studies.
How is the risk of a type I error increased?
- Not many studies that fail to reject the null hypothesis are published
- Flexibility in choosing the DV, sample size, and covariates
- Reporting subsets
