1 1. (21.29) The post-lunch dip is the drop in mental alertness after a midday meal.Does an extract of the leaves of the ginkgo tree reduce the post-lunch dip?Assign healthy people aged 18 to 40 to take either ginkgo extract or a placebo pill.After lunch, ask them to read seven pages of random letters and place an X over every e.Count the number of misses per line read.eBookStep 1:What is a placebo and why was one group given a placebo?True or False:A placebo allows researchers to asses the active concentration of ginkgo in the extract.O TrueO FalseStep 2:What is the double-blind method and why should it be used in this experiment?Neither the subjects nor the researchers who worked with them knew who was getting ginkgo extract.This prevents expectations or prejudices from affecting the evaluation of the effectiveness of the treatment.The researchers who worked with the subjects did not know which of the subjects was getting ginkgo extract.This prevents expectations from affecting the evaluation of the effectiveness of the treatment.O The researchers and subjects did not meet each other, to prevent non relevant considerations in the evaluation of the effectiveness of the treatment.The subjects did not know who was getting ginkgo extract.This prevents expectations or prejudices from affecting the evaluation of the effectiveness of the treatment.Step 3:Here are summaries of performance after 13 weeks of either ginkgo extract or placebo:GroupGroup sizeМeanStd. devGinkgo210.06383 0.01462Placebo180.05342 0.01549Is there a significant difference between the two groups?Give the two sample test statistic.Give your answer to 3 decimal places. Step 4:Give the P-value to evaluate if a significant difference exists between the two groups.O 0.04 < P< 0.0o5O 0.05 < P< 0.10OP> 0.10OP< 0.025Step 5:What do these data show about the effect of ginkgo extract?O we have strong evidence, at the 1% level, that those who took gingko extract had more misses per line.O The data do not give significant evidence, at the 5% level, that those who took gingko extract had more misses per line.O we have significant evidence, at the 5% level, that ginkgo extract does not reduce post lunch dip.O we have evidence, significant at the 5% level, that those who took gingko extract had more misses per line.

Solution In double-blinded method neither the experimenters nor the participants know which…

1.29) The post-lunch dip is the drop in mental alertness after a midday meal. Does an extract of the leaves of the ginkgo tree reduce the post-lunch dip? Assign healthy people aged 18 to 4o to take either ginkgo extract or a placebo pill. After lunch, ask them to read seven pages of random letters and place an X over every e. Count the number of misses per line read. eBook Step 1: What is a placebo and why was one group given a placebo? True or False: A placebo is a much less concentrated ginkgo extract. A placebo allows researchers to asses the active concentration of ginkgo in the extract. O True O False