Question

You, recently participated in an experiment to test the effectiveness of saturation patrol on residential burglaries. Prior to the experiment there were two neighborhoods (both about the same size) in your city with an equal number of residential burglaries. Burglaries in these neighborhoods were inordinately high.

Prior to the experiment both neighborhoods had the same number of patrol officers assigned to them across all shifts. The captain assigned twice the normal number of patrol officers to work in Neighborhood A (i.e. saturation patrol) in an effort to deter future burglaries. The captain did not change the normal number of patrol officers to work in Neighborhood B.

At the end of six weeks the number of residential burglaries decreased in Neighborhood A but remained the same in Neighborhood B. The chief wants to know if the difference in residential burglaries between these two neighborhoods is statistically significant, i.e. not due to change. Answer the following questions.

1. What is the independent variable in this experiment?

2. At what level (nominal, ordinal or scale) is the independent variable measured?

3. What is the dependent variable in this experiment?

4. At what level (nominal, ordinal or scale) is the dependent variable measured?

5. What is the null hypothesis for this experiment?

6. What is the alternative (research) hypothesis for this experiment?

7. What type of hypothesis (difference or association) is the alternative (research) hypothesis?

8. Which of the statistical techniques that you have learned so far (Chi-Square or t-test) would be the most appropriate to analyze the data in this experiment?

Answer 1

(1) The independent variable is the number of patrolmen in the neighborhoods A and B

(2) Since the independent variable is a number, it is a scale measurement.

(3) The dependent variable is number of burglaries in the neighborhoods A and B.

(4) Since the dependent variable is a number, it is a scale measurement.

(5) The null hypothesis is -

(6) The alternative hypothesis is

(7) The alternative hypothesis contains the 'not equal to ' sign '. Hence it is a difference.

(8) The most appropriate statistical technique for analysis would be t test for 2 independent samples