In: Statistics and Probability
A psychologist would like to determine whether there is a relation between depression and aging. It is known that the general population averages μ = 40 on a standardized depression test. The psychologist obtains a sample of n = 9 individuals who are all more than 70 years old. The depression scores for this sample are as follows.
50, 47, 41, 49, 44, 42, 43, 47, 48
On the basis of this sample, can the psychologist conclude that
depression for elderly people is significantly different from
depression in the general population? Use a two-tailed test at the
0.05 level of significance. (Round your answers to three decimal
places.)
t-critical = | ± |
t=
H0: = 40
Ha: 40
t critical value at 0.05 level for 8 df is 2.306
From the sample data
= 45.6667
S = 3.2404
Test statistics
t = - / S / sqrt(n)
= 45.6667 - 40 / 3.2404 / Sqrt(9)
= 5.2463
This is test statistics value.
Since Test statistics value > 2.306, we have sufficient evidence to reject H0.
We conclude at 0.05 level that depression for elderly people is significantly different from depression in the
general population.