Statistics for People Who (Think They) Hate Statistics

by Neil J. Salkind

can learn what test is related to what type of question in this part of the book. Computation of the test statistic value. The test statistic value (also called the obtained value or observed value) is the result or product of a specific statistical calculation. For example, there are test statistics for the significance of the difference between the averages of two groups, for the significance of the difference of a correlation coefficient from zero, and for the significance of the difference between two proportions. You’ll actually compute the test statistic and come up with a numerical value. Determination of the value needed for rejection of the null hypothesis using the appropriate table of critical values for the particular statistic. Each test statistic (along with group size and the risk you are willing to take) has a critical value associated with it. This is the value you would expect the test statistic to yield if the null hypothesis is indeed true. In practice, when computer software is used, these tables of critical values are replaced by the computer’s calculations. Comparison of the obtained value with the critical value. This is the crucial step. Here, the value you obtained from the test statistic (the one you computed) is compared with the value (the critical value) you would expect to find by chance alone. If the obtained value is more extreme than the critical value, the null hypothesis cannot be accepted. That is, the null hypothesis’s statement of equ...