The table below displays the results of a study investigating the effectiveness of bicycle safety helmets in preventing head injury. The data consist of a random sample of 793 bicyclists who were involved in bicycle accidents. Head Injury wearing Helmet Yes No Total Yes 17 218 235 No 130 428 558 Total 147 646 793 What is the probability of obtaining a head injury in a bicycle accident? 0.020 0.254 0.185 0.201 0.296

A 10-year study conducted by the American heart Association provided data on how age, blood pressure, and smoking relate to the risk of strokes. Assume that the following data are from a portion of this study. Risk is interpreted as the probability (times 100) that the patient will have a stroke over the next 10-year period. Risk Age Pressure Smoker 12 57 152 No 24 67 163 No 13 58 155 No 56 86 177 Yes 28 59 196 No 51 76 189 Yes 18 56 155 Yes 31 78 120 No 37 80 135 Yes 15 78 98 No 22 71 152 No 36 70 173 Yes 15 67 135 Yes 48 77 209 Yes 15 60 199 No 36 82 119 Yes 8 66 166 No 34 80 125 Yes 3 62 117 No 37 59 207 Yes (a) Develop an estimated regression equation that relates risk of a stroke to the person's age, blood pressure, and whether the person is a smoker. (Let x1 represent age, x2 represent blood pressure, x3 represent whether the person is a smoker, and y represent risk. For the smoking variable, define a dummy variable with 1…

A well-known psychology graduate program claims that their Ph.D. graduates get higher-paying jobs than the national average. Last year's figures for salaries paid to all graduates with a psych Ph.D. on their first job showed a mean of $6.20 per hour. A random sample of 10 graduates from last year's class of psychology Ph.D.s showed the following hourly salaries for their first job: $5.40 $6.30 $7.20 $6.80 $6.40 $5.70 $5.80 $6.60 $6.70 $6.90   (a) What is the alternative hypothesis?   (b) What is the null hypothesis?  (c) What can you conclude about the psychology graduate program's claim? Use an alpha level = .052tailed.  (d) What error might you be making by your conclusion in part (c)?  (e) If you were only concerned with evaluating whether salaries increased, how would this effect the power of your experiment?

A study of 3000 people compared the rates of liver cancer between 2000 people who drank one or more cup of coffee per day and 1000 people who drank less coffee than that. Of the coffee drinkers, 21 got liver cancer, while of the people who didn’t drink coffee, 20 got liver cancer. Do a hypothesis test for the question: “Is there an association between coffee drinking and liver cancer?” Interpret your results. Does coffee drinking increase, decrease or not affect the probability of getting liver cancer?

Estimates from the American Diabetes Association suggest that 10% of the American population has diabetes. According to recent research,[1] the prevalence of smoking is 25.7% among individuals with diabetes, and 24.1% among individuals without diabetes. If a smoker is selected at random, what is the probability that the individual has diabetes? What is the probability that a non-smoking individual actually does not have diabetes?

Suppose that asthma affects 1 in 20 children in a population. We decide to redo the survey and now take an SRS of 250 children from this population. What is the probability of observing at least 25 cases in a sample?

Suppose that asthma affects 1 in 20 children in a population. You take an SRS of 50 children from this population. What is the probability of observing at least five cases in a sample?

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The expected relative frequency of a particular outcome is?

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