Although many different levels of confidence have been used, (17)________ and (18)________ are the most prevalent. Confidence intervals are more narrow or precise when standard error is smaller. Since standard error is reduced when sample size is increased, the larger the sample size, the more precise the confidence interval.

In the behavioral science, hypothesis tests have been preferred to confidence intervals. However, (19)______________________________________________ are more informative because they indicate the size of the (20)________________. A hypothesis test is most appropriate when the major concern is whether or not an (21)________________________ is present.