suppose approximately 900 people die in bicycle accidents each year one study ea

Question

suppose approximately 900 people die in bicycle accidents each year one study eamined he records of s bicyclists aged 15 or older who were fatally injured in bicyde accidents a five-year period and were tested or alkeheln of these, s42 terted pasitive for akehal (blood alcahol concentration of in 0.01 or higher). (a) summarine the data with appropriate descriptive statistics. (Round your answer to four decimal places.) (b) To do statistical inference for these data, we think in terms of a model wherep n parameter that represarts the prebabaty that a tested bicycle rider is pesitve far aleehol. Find .ssru condence interval for (Reund your answers to four decimal places.) (c) Can you conclude from your analysis of this study that alehel causes fatal bicycle accidents? Explain. O Yesi we know that of the soo people that die in bicycle accidents each vear, about 542 test positive for alcohol. O Nen we de net know, for example, what percentage of cyclists whe were net involved in fatal dents had woehol in their ystems. (d) In this study 400 bicyclists had bload alcohol level above 0.10% v. level defining legally dunk at the time. ove a confidence interval for the preportian who were legally drunk according to this criterion. Round your answers to four decimal places.)

Explanation / Answer

(a) n=1911, x=number of alchohalic positive=542

p=x/n=542/1911=0.2836

(b) SE(p)=sqrt(p(1-p)/N)=sqrt(0.2836*(1-0.2836)/1911)=0.0103

(1-alpha)*100% confidence interval for p=p± z(alpha/2)*SE(p)

99% confidence interval for p=0.2836±z(0.01/2)*0.0103=0.2836±2.5758*0.0103=0.2836±0.0265=(0.2571,0.3101)

(c) right choice is second, No.......

(d) here, p=400/1911=0.2093

SE(p)=sqrt(0.2093*(1-0.2093)/1911)=0.0093

99% confidence interval for p=0.2093±z(0.01/2)*0.0093=0.2093±2.5758*0.0093=0.2093±0.0239=(0.1854,0.2232)

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