Marriage In 1960, census results indicated that the age at which American men first married had a mean of 23.3 years. It is widely suspected that young people today are waiting longer to get married. We want to find out if the mean age of first marriage has increased during the past 40 years. a) Write appropriate hypotheses. b) We plan to test our hypothesis by selecting a random sample of 40 men who married for the first time last year. Do you think the necessary assumptions for inference are satisfied? Explain. c) Describe the approximate sampling distribution model for the mean age in such samples. d) The men in our sample married at an average age of 24.2 years, with a standard deviation of 5.3 years. Whats the P-value for this result? e) Explain (in context) what this P-value means. f) Whats your conclusion?
SE(X) measures how close the sample AVG is likely to be to the true population AVG ● What’s the problem here –SE(X) depends on population SD –we don’t know population SD ● How could you approximate the populaUse() ̂ (called “hat”) means estimate or predicted () () = √ Confidence Interval (CI): a range of values (%) that catches the average/mean of the population Margin of Error Margin of Error Interpretation of Confidence Interval: __% of all samples will