# hypothesis testing on biostatistics

1. The mean lifetime for cardiac stents is 8.9 years. A medical device company has implemented some improvements in the manufacturing process and hypothesizes that the lifetime is now longer. A study of 40 new devices reveals a mean lifetime of 9.7 years with a standard deviation of 3.4 years. Is there a statistical evidence of a prolonged lifetime of the stents? Run the test at a 5% level of significance.

2. The Table below displays descriptive statistics on subjects involved in a clinical trial. Are any of the characteristics significantly different between groups? Justify briefly.

New Compound Placebo p-value

Mean age (years) 47.2 46.1 0.7564

Men (%) 44 59 0.0215

Mean educational level (years) 13.1 14.2 0.6898

Mean annual income $36,560 $37,470 0.546

Mean body mass index (BMI) 24.7 25.1 0.0851

https://brainmass.com/statistics/descriptive-statistics/hypothesis-testing-biostatistics-549084

#### Solution Preview

1. Let mu be the mean lifetime for cardiac stents

Ho: mu=8.9 vs. Ha: mu>8.9

Test statistic=(9.7-8.9)/[3.4/sqrt(40)]=1.4881

At level 5% ...

#### Solution Summary

The solution gived detailed steps on conducting the hypothesis testing which is done by excel. All formula and calculations are shown and explained.