Discussion Week 5_ HYPOTHESIS TEST FOR A MEAN

Response 2: Instructions

When performing a hypothesis test, it is important to remember that we are not proving the results to be true. The data comes from a sample and a different sample could result in a different conclusion. Therefore, a hypothesis is stated to be supported, not proven. Choose one (1) peer, examine their conclusion, and then answer the following questions:

· What is one (1) lurking variable that you think might sway the test so that the opposite hypothesis is supported?

· Why do you feel this would be an important variable that might change the results?

Louann Visconti

You are interested in determining if smokers have a BMI that is greater than non-smokers.

1. Explain which hypothesis test would be appropriate for this situation. Assume population variances are not known, sample variances are not equal, and alpha=0.05.

The two sample t-test with unequal variance would be used to compare the two samples and provide the variance to complete the z-test.

2. Explain if the test is a left-, right-, or two-tailed test. Justify your choice.

This is a right tailed test because we are determining whether or not the smokers BMI is greater than nonsmokers BMI. The null hypothesis is that the mean values are equal and the alternative hypothesis is that the smokers BMI is  greater than the nonsmokers BMI. This indicates a right tailed test.

3. Complete a hypothesis test in Excel to test your claim. Be sure to include the results from the data analysis tool pack test.

m1: Mean of Smokers

m2: Mean of Nonsmokers

Ho: m1=m2

H1: m1>m2

t-Test: Two-Sample Assuming Unequal Variances
	Smokers BMI	Non smokers BMI
Mean	28.2823529	28.4533333
Variance	30.6863458	28.1894713
Observations	34	30
Hypothesized Mean Difference	0
df	62
t Stat	-0.1259735
P(T<=t) one-tail	0.45008025
t Critical one-tail	1.66980416
P(T<=t) two-tail	0.90016051
t Critical two-tail	1.99897152

 

4. Write a conclusion statement that makes use of Excel data to justify which hypothesis is supported and why.

Because the P-value of 0.45 is greater than the significance level of a=0.05 we fail to reject Ho. This means that there is insufficient evidence to support the claim that smokers have a greater BMI than nonsmokers.

5. State your decision in the context of the research question: Do smokers have a BMI that is greater than nonsmokers?

Based on the statistics, smokers do not have a greater BMI than nonsmokers.