ISI
Lab 4

1: Introduction 2: Files Needed 3: Explore data 4: Numerical 5: Graphical 6: Discussion 7: Thought Questions 8: Statistical Inference 9: Two Proportions Applet 10: Analysis 11: Confession 12: Confidence Interval 13: Conclusions 14: Summary

Numerical Summary

(d) To numerically compare the two groups, we want to calculate the proportion of "successes" separately for each group. When we "condition" the proportion based on the different groups, these are called conditional proportions. Calculate (by hand) the conditional proportion who yawned in each group and the observed difference as follows:

Of the 34 subjects in the Seeded group, what proportion of these subjects yawned?

Of the 16 subjects in the Control (no seeding) group, what proportion of these subjects yawned?

Calculate the difference in these conditional proportions:

Sidenote: It's actually easier to interpret this difference in terms of proportions. If you convert to percentages, it's too easy for example to say "the difference was 10%" when you really mean "10 percentage points." An "increase of 10%" implies multiplication (by 1.10), not adding 0.10.

Show your calculations in the Numerical Summary section of your lab report. Then return here and press Next for further instructions.