Describe standardization and the roles of the normal curve, the Flynn effect, reliability (test-retest and split-half), and validity (content and predictive). Analyze the normal curve of intelligence testing and explain the mean, standard deviation, and percentiles for the data. You can access the data in PDF or word-processing format.

The difference of sample means of two populations is 55.4, and the standard deviation of the difference of sample means is 28.1. which statement is true if we are testing the null hypothesis at the 95% confidence level? a. the difference of the two means is significant, so the null hypothesis must be rejected. b. the difference of the two means is significant, so the null hypothesis must be accepted. c. the difference of the two means is not significant, so the null hypothesis must be rejected. d. the difference of the two means is not significant, so the null hypothesis must be accepted.