A clinical psychologist posits that drug use leads to conduct problems. To test this, he examines whether his adolescent inpatient drug users were elevated in terms of conduct disorder (CD). A sample of 100 was evaluated using a standard measure of CD; they had a mean score of 53. The population mean (µ) for the CD scale is 50 with a standard deviation (σ) of 10. (Show all work.)   What are the null and alternative hypotheses?   Using an alpha level of .05, determine whether his sample was significantly different from population.   Report and interpret an effect size.

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Q: Compute the value of the test statistic.

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Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.