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Section Homework 1.1 26. (a) Research objective: To determine if blood pressure level is associated with dietary micronutrients in adolescents at risk for hypertension. (b) Sample: A group of randomly selected adolescents, aged 14 to 16 years, who had high blood pressure. (c) Descriptive statistics: The subjects were classified into 4 groups according to gender and folic acid intake. The average diastolic blood pressure was calculated for each group. Male and low-folate: 72 mm Hg Male and high-folate: 67 mm Hg Female and low-folate: 76 mm Hg Female and high-folate: 73 mm Hg (d) Conclusions: For adolescents at risk for high blood pressure, a diet rich in folic acid can contribute to the prevention of hypertension when instituted at an early age. 28. (a) Research objective: To determine whether Propecia is effective in the treatment of male pattern hair loss on the vertex and anterior mid-scalp area in men. (b) Sample: Consisted of over 1800 men aged 18 to 41 with mild to moderate amounts of ongoing hair loss. (c) Descriptive statistics: The researchers measured hair counts in the men before and after taking either Propecia or a placebo. There was an increase in hair count for those taking Propecia but a continuing decrease for the placebo group. (d) Conclusions: Propecia is effective in maintaining or increasing the amount of hair on the vertex and anterior mid-scalp area. 32. Individuals: The six different car models forming the BMW product line. Variables: Data: Body style qualitative Coupe, convertible, or Sedan Weight quantitative, continuous Pounds # of seats quantitative, discrete 2 or 5 seats
Section 1.2 2. Experiment. 8. Observational study. 10. Experiment. Section 1.3 2. Cluster. 4. Stratified. Section 1.4 2. (a) Flawed sampling (b) method. Assuming that households within any given neighborhood have similar household incomes, stratified sampling might be appropriate, with neighborhoods as the strata. 6. (a) Flawed survey because of non-response. (b) Petland could provide an incentive (such as a coupon) for responding to the survey. However, that might only elicit responses from some pet-owners and none from those who don't have pets (biased sample). A better design might be to use telephone interviews. Section 1.5 2. (a) Cold symptoms present. (Yes or no) (b) Treatment: Medication Levels: 2 (Drug, placebo)
(c) Gender, age and location are controlled for. (d) The subjects are all from the same city. (e) Extraneous variables are dealt with by a completely randomized design. The variables gender, age and location were held constant. (f) Experimental Units: 300 males with colds.
(g)
Treatment 1 Experimental Drug Group 1 150 males
Random assignment of 300 males to treatments
Compare cold symptoms
Treatment 2 Placebo
Group 2 150 males
4.
(a) Number of truancies. (...