AP Statistics Friday, 11 October 2013 OBJECTIVE TSW review for Tuesday’s test covering Chapter 2. ASSIGNMENTS DUE –Sec. 2.4: pp (2.38 – 2.44 all)  wire basket –WS Gallup Poll  black tray ASSIGNMENTS DUE TUESDAY –WS AP Questions #1 –WS AP Questions #2

Test Topics: Chapter 2 Know and use the following: –Population –Sample –Census –Sampling design –Sampling frame –Random digit table –Bias

Identify and know the advantages and disadvantages: –Simple random sample (SRS) –Stratified random sample –Systematic random sample –Cluster sample –Multistage sample Test Topics: Chapter 2

Identify sources of bias: –Voluntary response –Convenience sampling –Undercoverage –Nonresponse –Response bias –Wording of the questions Test Topics: Chapter 2

Know the following: –Observational study –Experiment –Experimental unit –Factor –Level –Response variable –Treatment –Control group –Placebo –Blinding –Double blind –Confounding variable Test Topics: Chapter 2

Know and describe the three principles of experimental design –Control –Randomization –Replication Wear Falcon Statistics shirt to receive a drop daily grade. Test Topics: Chapter 2

WS Experimental Design WS #2 1)a)factor – type of dog food with 2 levels (new & old) b)response variable – improvement in kidney health c)2 treatment groups – new dog food & old dog food

WS Experimental Design WS #2 2)a)2 factors – type walking device with 3 levels (none, standard walker & rolling walker) & type of response with 2 levels (response required & no response required) b)response variable – cadence c)6 treatment groups – no walker with response, no walker w/o response, standard walker with response, standard walker w/o response, rolling walker with response, rolling walker w/o response

WS Experimental Design WS #2 3)There is one factor – method of insulin delivery with two levels (inhaler or shots) that produce two treatment groups. I would do a completely randomized experiment where I assign the 100 patients to one of the two treatments. I would number the patients 1-100, writing the numbers on slips of paper and placing in a hat. I would randomly select 50 numbers from the hat and the corresponding patients would receive the inhaler. The remaining patients would receive the shots. After 6 months, I would measure the effectiveness of each method.

WS Experimental Design WS #2 4)The above experiment is not blinded to the patient (trust me – they know if they are getting a shot!) It can be blinded to the evaluator who determines the effectiveness of the methods. * If I want to blind the patients (exp. Units) then I could have them do both treatments where one is has insulin & one has a placebo – Treatment 1:inhaler w/insulin & shot w/placebo Treatment 2:inhaler w/placebo & shot w/insulin

WS Experimental Design WS #2 5)The factor is the type of fertilizer with three levels - producing 3 treatment groups, fertilizer A, B, & C. Suppose I had 15 plots of land (OK to make this up). I would number the plots 1-15, placing the numbers on slips of paper & putting into a hat. I would randomly select 5 numbers & the corresponding plots would receive fertilizer A, the next five numbers receive fertilizer B & the remaining 5 plots receive fertilizer C. I would measure the amount of corn produced. With a completely randomized design (as above) there are NO confounding variables! However, I would want to control for extraneous variable such as soil type, amount of rain or water, etc. Anything that I can’t control has then been evenly dispersed into all treatment groups through the use of randomization!

WS Experimental Extra Problems 1)a)completely randomized b)none c)migraine sufferers d)2 factors: type of medication with 2 levels (pain reliever or placebo) & ice water with 2 levels (drinks H 2 O or doesn’t drink H 2 O) e)4 treatment groups: pain reliever w/ ice water, pain reliever w/o ice water, placebo w/ ice water, placebo w/o ice water f)pain relieve g)patients can be blinded to type of medication, but not blinded to ice water h)Since several patients were used, hopefully it was enough to have more than one exp. Unit in each treatment group. Patients should be randomly assigned to one of the 4 treatments.

WS Experimental Design WS #2 2)a)randomize block b)blocked by estrogen usage c)menopausal women d)one factor: type of beverage with 2 levels (alcohol & no alcohol) e)4 treatment groups: estrogen users w/ alcohol, estrogen users w/o alcohol, non-estrogen users w/alcohol, & non- estrogen users w/o alcohol f)estrogen level in blood g)this could be double-blinded if the women could not tell if the beverage contained alcohol or not & the evaluator performing the blood test doesn’t know which group the women are in h)have replication with 6 in each treatment, women should randomly assigned to treatments

WS Experimental Design WS #2 3)a)matched pairs (randomized block) b)blocked by location c)locations in garden d)1 factor: type of trap with 2 levels (trap A & B) e)2 treatments: traps A & B f)number of bugs in traps g)none h)replication with 10 locations, should randomly assign which trap on right vs. left

WS Experimental Design WS #2 4)a)completely randomized b)none c)people with insomnia d)2 factors: type of diet with 2 levels (dessert & no dessert) & level of exercise (exercise & no exercise) e)4 treatment groups: dessert w/ exercise, dessert w/o exercise, no dessert w/ exercise, no dessert w/o exercise f)improvement in sleep g)none h)have replication, people should be randomly assigned to the 4 treatments

WS AP Review Design # Question 2 I would perform a matched-pairs design in which I would pair tanks 1 & 4, 2 & 3, 5 & 8, and 6 & 7 since they will potentially have the same temperature gradient. I will flip a coin to decide which food tank 1 will receive, heads receives “new” food and tails receives “old” food. Then tank 4 receives the other food. I will assign food to the other pairs of tanks in the same way. I will measure the weight gain of the salmon.

1999 Question 3 a)It is not an experiment because no treatments are imposed. (OR There is no random assignment of subjects to treatments OR existing data is being used.) b)Two variables are confounding if their effects on the number of cavities cannot be distinguished from one another. One possible confounding variable is that the people who eat an apple a day are more nutrition conscious and have a more healthy diet in general than those who eat one or fewer apples per week. c) No, this was not an experiment. (OR too many confounding variables) WS AP Review Design #1

2000 Question 5 a)I would write the volunteers’ names on slips of paper, put them in a hat, mix well, randomly pick half the names, and assign them to the “new” drug. The remaining volunteers will be assigned to the “current” drug. After six months, check the cholesterol levels of the volunteers and compare the two groups. b) I would divide the volunteers into two groups, those who exercise and those who do not exercise. (Explain why if some other block is used) Then I would randomly assign half of each group to the “new” drug by drawing their names from a hat. The remaining half of each group would receive the “current” drug. c)Yes, neither the subjects nor those administering the drugs or monitoring results should know which of the two drugs is being used. WS AP Review Design #1

1.E 2.B 3.B 4.D 5.E 6.C 7.D 8.B 9.A 10.E 11.A 12.C 13.C 14.A 15.D WS AP Review Design #2