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Sampling Distribution Video: t-Test

Figure 1. In this particular run of the simulation, the Type-I error rate (Green) was 5.9% (instead of the nominal 5%). The Type-II error (Blue) was 75% for a statistical power of about 25%. If my students did indeed have an immediate memory span of 7.4 items rather than the 7.7 reported by Cavanaugh, I only had about 1 chance in 4 of making a correct decision with my class of 20 students. This video recorded the actual time to complete the simulation which was less than a minute--about 40 seconds.