Question

Left ventricular mass (LVM) is an important risk factor for subsequent cardiovascular disease. A study is proposed to assess the relationship between childhood blood pressure levels and LVM in children as determined from echocardiograms. The goal is to stratify children into a normal bp group (< 80th percentile for their age, gender, and height) and an elevated bp group (≥ 90th percentile for their age, gender, and height) and compare change in LVM between the 2 groups. Before this can be done, one needs to demonstrate that LVM actually changes in children over a 4-year period.

To help plan the main study, a pilot study is conducted where echocardiograms are obtained from 10 random children from the Bogalusa Heart Study at baseline and after 4 years of follow-up.

ID	Baseline LVM (g)	4-year LVM (g)	Change (g)*
1	139	163	24
2	134	126	-8
3	86	142	56
4	98	96	-2
5	78	111	33
6	90	108	18
7	102	167	65
8	73	82	9
9	93	77	-16
10	162	172	10
Mean	105.5	124.4	18.9
sd	29.4	35.2	26.4

Implement an appropriate 2-sided test to test the hypothesis that there is a change in mean LVM over 4 years?

You must clearly write out all 4 steps of the appropriate hypothesis test clearly defining the parameter(s) involved, calculate the value of the test statistic and the p-value, and state your conclusion in the context of the problem.

Answer 1

We will be performing Paired sample t-test for hypothesis testing. Following are steps involved:

Thus, it can be concluded that there is not enough evidence to support the claim that there is a change in mean LVM over 4 years, at 5% significance level.