1). When there is a significant difference in the population, but the research fails to find one ...this is what kind of error?

Type I errorType II Error

2).

A personnel director at a very large corporation wants to see if her administrative assistants can type faster (i.e., more words per minute) than the national average of 50 words per minute.She tests 60 of her administrative assistants and finds their average words per minute is 50.5 with a standard deviation of 4.5.Using a 0.05 significance level, the personnel director finds the following:

H₁:> 50

z: 1.65

z = 0.861

Based on this information, what would you conclude?

Fail to reject the null hypothesis

Reject the null hypothesis

3).

In general, five year olds can complete a spatial reasoning test in approximately 8 seconds.A preschool teacher wants to see how her kids in her school fair on the test.She administers the test to the 55 students in her class and finds that on average they complete the test in 12.3 seconds, with a standard deviation of 9.8.Using a 0.01 significance level, he teacher finds the following:

H₁:8

z: +/- 2.57

z = -3.26

Based on this information, what would you conclude?

Fail to reject the null hypothesis

Reject the null hypothesis

4).

Assume that when victims are asked how well their needs were met by the criminal justice system on a scale of 1 (not met at all) to 5 (met completely), the average response is 3.24. In a study of 130 victims, Brewster (2001) found that the average response to how police officers met victims needs was 2.90 (standard deviation = 1.44). Perform a hypothesis test to determine if police officers respond less well to victims needs than the criminal justice system as a whole. Use a 0.05 level of statistical significance.

What's your critical value?

-1.96 1.96 1.65 -1.65

5).

Some research suggests that police officers are more likely to make an arrest in the presence of bystanders. If mentally disordered suspects attract more attention from bystanders, they may be more likely to be arrested than nonmentally disordered suspects. Assume that the average number of bystanders when police encounter a suspect is 3.58. In a sample of20 police encounters with mentally disordered suspects, Engel and Silver (2001) found an average of 7.03 bystanders (standard deviation = 9.42). Perform a hypothesis test to determine if there are more bystanders when the suspect is mentally disordered. Use a 0.01 level of statistical significance.

What's your critical value?

-2.528 2.528

2.539

-2.539