Exam 8: Confidence Intervals, Effect Size, and Statistical Power

A point estimate offers an advantage over an interval estimate because it estimates the population parameter using a range of values rather than a single number.

One of the roles of the researcher performing a meta-analysis is to:

Both effect size and the value of the test statistic are unaffected by changes in the sample size (holding other factors constant).

Two-tailed tests have more statistical power than one-tailed tests.

If a real difference exists between a sample and the comparison distribution, that difference is necessarily important and meaningful.

If an effect is significant but the effect size for the difference between the two means is medium (according to Cohen's conventions), about how much overlap will there be between the two distributions?

A Cohen's d value of 0.2 indicates how much overlap between distributions?

Meta-analysis involves:

Statistical power is calculated as 0.93.This means that if the null hypothesis is _____, there is a _____ percent chance of rejecting the null hypothesis.

A behavioral neuroscientist is testing the effects of adrenaline on memory using a group of 12 rats.The researcher is unsure about how much adrenaline might produce an effect on memory.One group of rats will be injected with placebo saline (0 micrograms of adrenaline).The other group will be injected with a dose of adrenaline.When deciding between a 2-microgram dose or an 8-microgram dose (both of which are safe), the researcher opts to use the 8-microgram dose.The researcher has:

As sample size increases, the test statistic increases because the:

If the mean difference between levels of the independent variable are exaggerated, statistical power:

Sample size can affect whether statistically significant differences are found, but sometimes in extremely large samples differences are found that are significant but of no real value or interest.What standardized value helps measure the size of the difference in relation to the variability of the data rather than to that of sample size?

Before conducting a power analysis, a researcher should know the desired:

The _____ estimate acknowledges the amount of uncertainty in the _____ estimate by reporting the margin of error.

A Cohen's d of -0.19 is what type of effect size?

If a researcher performs a meta-analysis and finds that the mean d = 0.45, and the 95 percent confidence interval around this mean is (0.34, 0.56), what can the researcher conclude?

A small difference between means may not be statistically significant with a small sample, but it could reach statistical significance with a large sample because:

The practical use of statistical power is that it informs researchers:

Meta-analysis includes an assessment of null effects, often called a file drawer analysis.