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Using SPSS to Compare Means . UDP 520 Lab 4 Lin Lin November 6 th , 2007. Outline. Dataset Independent samples Paired samples . Dataset—Weight Lost Training Program (WLTP) .
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Using SPSS to Compare Means UDP 520 Lab 4 Lin Lin November 6th, 2007
Outline • Dataset • Independent samples • Paired samples
Dataset—Weight Lost Training Program (WLTP) • 1000 adults aged 18+ (including both males and females) were recruited to study the effectiveness of Weight Lost Training Program. • Variables • Sex • BMI_1(before WLTP) • BMI_2(after WLTP) • Download dataset from http://courses.washington.edu/urbdp520/UDP520/WLTP_new.sav
Questions • Question one: • Is BMI significantly different between males and females before WLTP? • Question two: • Overall (for both males and females), is WLTP effective?
Question One • Step one: Making assumptions and meeting test requirements • Random sampling • Level of measurement is interval-ratio • Sampling distribution is normal • Step two: stating the null hypothesis • Step three: selecting the sampling distribution and establishing the critical region • Sampling distribution = Z distribution • Alpha=0.05, two-tailed • Z(critical)= 1.96
Question One (cont.)Step four: computing the test statistic in SPSS
Question One (cont.) • Step five: making a decision and interpreting the results of the test result or Z (obtained)
Question Two • Step one: Making assumptions and meeting test requirements • Random sampling • Level of measurement is interval-ratio • Sampling distribution is normal • Step two: stating the null hypothesis • Step three: selecting the sampling distribution and establishing the critical region • Sampling distribution = Z distribution • Alpha=0.05, two-tailed • Z(critical)= 1.96
Question Two (cont.)Step four: computing the test statistic in SPSS
Question Two (cont.) • Step five: making a decision and interpreting the results of the test result or Z (obtained)
Exercises • Is BMI significantly different between males and females after WLTP? • Is WLTP effective for males? • Hint (do selection in “Data”— “Select cases”— “if condition is satisfied”— “if”— “sex=0”) • Is WLTP effective for females?