Doctorate in Clinical Psychology (DClinPsy) Research Methods Practice Test

The Kolmogorov-Smirnov test is used to compare a sample distribution to a reference probability distribution or to compare two sample distributions. The test statistic that is calculated from the data is denoted by the letter D. This statistic measures the largest difference between the empirical distribution functions of the two samples or between the sample and the reference distribution.

Understanding the significance of D is crucial in interpreting the results of the Kolmogorov-Smirnov test, as it is the value that determines the distance between the two cumulative distribution functions being compared. The larger the value of D, the stronger the evidence against the null hypothesis, which states that the distributions are the same. Thus, knowing that D is the symbol used aids in successfully identifying the test's output and interpreting its implications in research settings.

The other options represent symbols associated with different statistical concepts or tests.