1. Hypothesis Testing
2011, 10, 25

2. Objectives Review distribution of sample means
Descriptive statistics vs. inferential statistics
Research hypothesis*
Statistical hypothesis testing – One sample z test**

3. Population
For IQ Score
= sample mean;
n=75
Distribution of
Sample Means
Probability
Means

4. Descriptive statistics vs. inferential statistics
procedures that help
us organize and
describe data collected
from either a a sample
or a population
Inferential Statistics:
The logic and procedures
concerned with making
predictions of inferences
about the population from
observations and analyses
of a sample

5. Research Hypothesis Law & Order Not Guilty Guilty Reject it! Mutually
Exclusive
Supported

6. Research Hypothesis (Two-Tailed Test)
The police department of a major city reports that the mean number of auto thefts per neighborhood per year is () 6.88 with a standard deviation () of As the mayor of a suburban community just outside the major city, you’re curious as to how the auto theft rate in your community compares.
 = 6.88
  6.88
Reject it!
Mutually
Exclusive
Supported

7. Research Hypothesis (One-Tailed Test)
Information collected at a local university indicates that students are working on average () 15.2 hours per week while in school with a standard deviation () of 3.5 hours. A research suspects that fraternity members work less than the school average. Information collected from a random sample of 30 fraternity members, reveals a mean of 13.9 hours per week.
  15.2
 < 15.2
Reject it!
Mutually
Exclusive
Supported

8. Probability Population For College Students’ = sample mean
Working Hours
= sample mean
n = 30
Probability

9. One-Sample z-Test Step 1: State hypotheses
Step 2: Set your decision criteria
Step 3: Compute mean and Std. Err.
Step 4: Compute the zobs score (test statistic)

10. One-Sample z-Test
Step 5: Make a decision about your null hypothesis

11. Lecture Recap: Hypothesis Testing
Review distribution of sample means
Descriptive statistics vs. inferential statistics
Research hypothesis*
Without direction: Two-tailed test
With direction: One-tailed test
One sample z test**
Five steps