Standardized measures seem to indicate that the aver- age level of anxiety has increased gradually over the past 50 years (Twenge, 2000). In the 1950s, the average score on the Child Manifest Anxiety Scale was μ = 15.1. A sample of n = 16 of today’s children produces a mean score of M = 23.3 with SS = 240. a. Based on the sample, has there been a significant change in the average level of anxiety since the 1950s? Use a two-tailed test with α = .01. b. Make a 90% confidence interval estimate of today’s population mean level of anxiety. c. Write a sentence that demonstrates how the outcome of the hypothesis test and the confidence interval would appear in a research report.
Standardized measures seem to indicate that the aver-
age level of anxiety has increased gradually over
the past 50 years (Twenge, 2000). In the 1950s, the
average score on the Child Manifest Anxiety Scale
was μ = 15.1. A sample of n = 16 of today’s
children produces a mean score of M = 23.3 with
SS = 240.
a. Based on the sample, has there been a significant
change in the average level of anxiety since the
1950s? Use a two-tailed test with α = .01.
b. Make a 90% confidence
today’s population mean level of anxiety.
c. Write a sentence that demonstrates how the
outcome of the hypothesis test and the confidence
interval would appear in a research report.
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