Standardized measures seem to indicate that the average 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  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 .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.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.3: Measures Of Spread
Problem 26PFA
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13. Standardized measures seem to indicate that the
average 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  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 .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.

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