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A study examines a group of mothers with young children who were receiving welfa

ID: 3234908 • Letter: A

Question

A study examines a group of mothers with young children who were receiving welfare last year. The women attended a voluntary job training program that was offered free of charge at a local vocational school and was advertised in the local news media. The study report says that with 95% confidence, the percent of the women still on welfare is 21% plusminus 4%. You are on the staff of a member of Congress who is interested in the plight of welfare mothers and who asks you about the report. a) Explain clearly and briefly what "95% confidence" means. b) Is this study good evidence that requiring job training of all welfare mothers would greatly reduce the percent who remain on welfare for several years? Think about the study design to answer this question.

Explanation / Answer

a) 95% confidence tells us that the proportion of women still on welfare after the training program can be estimated as 0.21 with a margin of error 0.04, with 95% confidence.

b) This experiment cannot be considered as random as the entry level in the training program is voluntary, thus this study is not a good evidence.