Experiment 1: Johnny Long-Arms throws Model-A paper airplane 15 times.  The sample average distance of Johnny’s Model A plane is 15.4 ft.  Gus Parker throws his Model-B paper airplane 15 times.  The sample average distance of Gus’s Model B plane is 7.1 ft.  The conclusion is drawn that the Model A plane is better than the Model B plane.  What is wrong with this conclusion?  What confounding variable has potential influence over the results?  How can control be established if we do want to compare Model A to Model B? Describe another way this experiment could violate control.

Experiment 2: A research company wants compare SAT scores between students who are assigned SAT practice problems for homework to students who are not.  Teachers of the Algebra 2M classes are asked to implement assigned SAT practice problems for homework, while teachers of Regular Algebra 2 classes are not.  The average SAT score of these two groups are compared.  In the end the research company concluded that SAT practice actually hindered student performance.  What is wrong with this conclusion?  What confounding variable has potential influence over the results?   How can control be established if we do want to compare SAT homework to no SAT homework? Describe another way this experiment could violate control.

Experiment 3: A research company wants to see whether cigarettes have an effect on the growth of grass.  They designate two areas.  One area is located in field A while another is located in field B.  Field A is treated with chemicals identical to those in cigarettes.  Field B is not treated with any chemicals.  After collecting data, it was concluded that cigarettes due in fact effect the growth of grass as it was found that the grass in field A was far less than that of field B.  What is wrong with this conclusion?  What confounding variable has potential influence over the results?   How can control be established if we do want to compare “cigarette” grass to “non-cigarette” grass? Describe another way this experiment could violate control.

Experiement 4: It is thought that males can sort a pack of cards into suits quicker than females.  It is also thought that poker players can sort a pack of cards into suits quicker than non-poker players.  An experiment is conducted where researchers time male poker players and compare these times to non-poker playing females.  The former group scored much better in their times and so it was concluded that males sort cards better than females and poker players sort cards better than non-poker players.  What is wrong with this conclusion?  What sound conclusion can be drawn from this study? Describe another way this experiment could violate control.

Experiment 5: A new drug is to be tested as to its effectiveness on depression. The population of interest is all patients diagnosed with clinical depression. Describe the experiment using a Completely Randomized Design (CRD). Discuss the role of a placebo. Discribe the difference between the control group and the experimental group(s). What is meant by a double-blind experiment? Describe the experiment using a Randomized Complete Block (RCB).