Paired t-test example for statistics students
Not what you're looking for?
Community policing strategies have been useful in some jurisdictions to reduce crime. As Police Captain, you wish to run an experiment to see whether it will work in your city. In each of 10 neighborhoods you record the number of arrests for violent offenses for 90 days prior to implementing a community policing strategy and for 90 days after the program has been running for 6 months.
Neighborhood Before After
1 55 42
2 62 59
3 57 58
4 69 60
5 65 58
6 88 81
7 76 70
8 55 51
9 54 56
10 65 63
SUM
646 598
Did community policing work? What are the null and alternative hypotheses? What is your conclusion [use alpha of 1%]?
Purchase this Solution
Solution Summary
A complete worked through solution for a paired t-test statistics problem.
Solution Preview
For this question you will need to do a paired t test as both data sets come from the same neighborhood, or the "before and after" type of experiment design.
The following formula will be used:
t observed = dbar - md/ sdbar
Where dbar is the average of all difference values between sets, md is equal to 0 (because of paired data), and sdbar is equal to sd/square root n.
The null hypothesis in this case is that there will not be a difference in mean violent crime offenses before and after implementing a community policing strategy.
Ho: mean before = mean after.
The alternative hypothesis is that there will be a difference between mean violent crime offenses before and after the policing strategry is implemented.
Ha: ...
Purchase this Solution
Free BrainMass Quizzes
Terms and Definitions for Statistics
This quiz covers basic terms and definitions of statistics.
Measures of Central Tendency
This quiz evaluates the students understanding of the measures of central tendency seen in statistics. This quiz is specifically designed to incorporate the measures of central tendency as they relate to psychological research.
Measures of Central Tendency
Tests knowledge of the three main measures of central tendency, including some simple calculation questions.
Know Your Statistical Concepts
Each question is a choice-summary multiple choice question that presents you with a statistical concept and then 4 numbered statements. You must decide which (if any) of the numbered statements is/are true as they relate to the statistical concept.