chapt 5 practices NIBRS-GSS / CJ STATS
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NIBRSChapter51.docxCJ 317 CJ Statistics
Chapter 5 – NIBRS Exercises
Let’s work with our assault cases again.
1. Find the mean and standard deviation for offender age.
a. Using the mean and standard deviation, what percentage of offenders are over 18?
b. What percentage of offenders are over 21?
c. What is the probability of selecting at random an offender who is under 18?
2. Using the frequencies procedure (ANALYZE, DESCRIPTIVE STATISTICS, FREQUENCIES), request a histogram of victim age with the normal curve overlay (from the Charts button), as well as the mean and standard deviation (from the Statistics button).
a. Comment on the closeness of the actual distribution to the normal curve.
b. Based on the normal distribution (using the z score and Table A), what is the probability that a victim is under 13?
3. Using the frequencies procedure (ANALYZE, DESCRIPTIVE STATISTICS, FREQUENCIES), request a histogram of offender age with the normal curve overlay (from the Charts button), as well as the mean and standard deviation (from the Statistics button). Comment on the closeness of the actual distribution to the normal curve.
