Section 3:

Interpretation of data analyses Refer to the excerpt titled Which city should AmlaG be marketed to? A mini case.

Mr. Agapito will design 2 research projects; the first project investigates the effect of 'shea oil' on change in hair length in men, while the second compares the impact of AmlaG and shea oil on change in hair length in children. In the first project, 100 participants applied 4.5 millilitres of shea oil to their scalp every day for 1 week. In the second research project, 75 participants applied 4.5 millilitres of shea oil to their scalp every day for 1 week, while 80 participants applied 4.5 millilitres of AmlaG to their scalp every day for 1 week. Hair measurements were in micrometres.

1. For the first research project:

a. what is the null hypothesis for the first research project?

b. what is the null hypothesis for the second research project?

c. Mr. Agapito ran a t-test on the data collected from the second research project. He conducted the analyses using RStudio and Microsoft Excel. The results were exactly the same with RStudio and Microsoft Excel and below is the output of the t-test. In the output, A corresponds to the 'shea oil' group

data: A and B

t = -0.067579, df = 239.15, p-value = 0.9462

alternative hypothesis: true difference in means is not equal to 0

95 percent confidence interval:

-5267.826 4918.385

sample estimates:

mean of A =10,333.55

mean of B =8,205.27

i. A t-test compares whether a difference between two means is significantly different.

What is meant by 'significantly' here?

The first research project examines a difference; the second research project also examines a difference? How is the difference in the first research project different from the difference in the second research project?