A random digit dialing telephone survey of 880 drivers asked, "Recalling the last ten traffic lights you drove through, how many of them were red when you entered the intersectinos?" Of the 880 respondents, 171 admitted that at least one light had been red.
a)Give a 95% confidence interval for the proportion of all drivers who ran one or more of the last ten red lights they met.
b) Nonresponse is a practical problem for this survey-only 21.6% of calls that reached a live person were completed. Another practical problem is that people may not give truthful answers. What is the likely direct of the fias: do you think more or fewer than 174 of the 880 respondents really ran a red light? Why?
This solution determines the likelihood of drivers running one or more of the last ten red lights and discusses the bias of answering surveys.