A researcher is evaluating whether an increase in the minimum hourly wage has had an effect on employment in the manufacturing industry in the following three months. Taking a sample of 25 firms, what should she conclude if (a) the mean decrease in employment is 9 percent, and the standard error of the mean is 5 percent; (b) the mean decrease is 12 percent, and the standard error is 5 percent; (c) the mean decrease is 20 percent, and the standard error is 5 percent?
Determine the 95 percent confidence interval for the effect of an increase in the minimum wage on employment, given the data in the question above, for part a and b. How do these confidence intervals relate to the results of the t tests in that exercise?