# Each year in Britain there is a No Smoking Day, where many people voluntarily stop smoking for a day

August 30, 2017

Question
How can you determine the 99% confidence interval in (b) of this problem using a TI-83 calculator?

1. Each year in Britain there is a No Smoking Day, where many people voluntarily stop smoking for

a day. This No Smoking Day occurs on the second Wednesday of March each year. Data are

collected about nonfatal injuries on the job, which allows a test of the hypothesis that stopping

smoking affects the injury rate. Many factors affect injury rate, though, such as year, time of work,

etc., so we would like to be able to control some of these factors, one way to do this is to compare

the injury rate on the Wednesday of the No Smoking Day to the rate for the previous Wednesday

in the same years. Those data for 1987 to 1996 are listed in the following table:

Year: 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996

before no smoking day: 516 610 581 586 554 632 479 583 445 522

on no smoking day: 540 620 599 639 607 603 519 560 515 556

(a) How many more or fewer injuries are there on No Smoking Day, on average, compared with