There have been many studies trying to link the association between different biomarkers and environmental measures of second hand smoke (SHS). Cotinine is the gold standard biomarker for airborne nicotine and in particular for SHS exposure assessment in children with asthma. (Household Smoking Behavior: Effects on Indoor Air Quality and Health of Urban Children with Asthma, Buty, Breysse, et. Al, Matern Child Heath J (2011) 15:460-468)
The bad thing about urine cotinine levels is that it is persistent and stays in the body for extended periods of time. So trying to relate urine cotinine to the number of cigarettes smoked in a home is really quite a hard thing to do because of this latent feature.
A new study was designed to measure the urine cotinine levels of long-distant haulers (truckers) who smoked. The study was trying to get an understanding of SHS in a confined area (the cab of the big rig) and an open area of the home.
Ten truckers were recruited for the study and the results were as follows. The condition being that the truckers had to be driving for a period of at least 8 hours and then their urine was immediately sampled versus the same trucker at home for at least one day before their urine was sampled. The truckers were not to deviate from their smoking habits. In other words, if they smoke six cigarettes every 8 hours in the truck, then they smoked six cigarettes every 8 hours at home.
Cotinine Concentrations (ng/ml)
Driver Truck Cab Home
1 325 273
2 288 280
3 295 260
4 424 413
5 375 297
6 455 386
7 365 410
8 424 406
9 289 261
10 381 415
From these data and using the dependent sample analysis approach, test the claim at 95% confidence that the urine cotinine concentrations in the truck cab were higher than those at home.
a) State the Null and Alternative Hypotheses (1)
b) Prepare the PDF and state the Decision Rule (1,1)
c) Determine the test statistic (8)
d) State your decision (1)
e) State the interpretation. (1)
f) Is your decision the same at 90% confidence? Explain. (1,1)