A psychologist is studying the self image of smokers, as measured by the self-image (SI) score from a personality inventory. She would like to examine the mean SI score, μ, for the population of all smokers. Previously published studies have indicated that the mean SI score for the population of all smokers is 82and that the standard deviation is 12, but the psychologist believes that the value for the mean has decreased. She plans to perform a statistical test. She takes a random sample of SI scores for smokers and computes the sample mean to be 7.Based on this information, answer the questions below. What are the null hypothesis (H0) and the alternative hypothesis (H1) that should be used for the test? H0: μ is ?less than less than or equal togreater thangreater than or equal to not equal toequal to ? 82 74 12 H1: μ is ?less thanless than or equal togreater thangreater than or equal tonot equal toequal to ? 82 74 12 In the context of this test, what is a Type II error? A Type II error is ? rejecting/failing to reject the hypothesis that μ is ? less than/less than or equal to greater thangreater than or equal tonot equal toequal to ? 82 74 12 when, in fact, μ is ? less than less than or equal to greater thangreater than or equal to not equal toequal to ? 82 74 12. Suppose that the psychologist decides to reject the null hypothesis. What sort of error might she be making? Type IType II
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
What are the null hypothesis (H0) and the alternative hypothesis (H1) that should be used for the test? H0: μ is ?less than less than or equal togreater thangreater than or equal to not equal toequal to ? 82 74 12 H1: μ is ?less thanless than or equal togreater thangreater than or equal tonot equal toequal to ? 82 74 12
A Type II error is ? rejecting/failing to reject the hypothesis that μ is ? less than/less than or equal to greater thangreater than or equal tonot equal toequal to ? 82 74 12 when, in fact, μ
Suppose that the psychologist decides to reject the null hypothesis. What sort of error might she be making? Type IType II |
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