# Confidence Intervals with 2 Samples 1 answer below »

For this Application Assignment, you complete three problems
in which you calculate confidence intervals with two samples.

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The difficult part is deciding whether the differences you
observe in two groups are statistically significant. The confidence intervals
can help you make that decision. When comparing the means of two groups,
subtract one mean from the other. If they are the same, the answer will be
zero. Remember that with the 95% confidence interval there is a range of values
that contain the true mean in 95 of 100 samples. If zero is part of that range
then the difference of the two means is not statistically significant. But what
happens when you are comparing odds as in odds ratios? Since this is a ratio,
divide the odds of one group by the odds of the other. If they are the same the
answer is one. Again, remember that with the 95% confidence interval there is a
range of values that contain the true mean in 95 of 100 samples. Now, however,
if one is part of that range the ratio of the two odds is not statistically
significant. Keep this in mind as you complete this week’s Application
Assignment.

• To
complete this Application Assignment, answer the following problems:

Problem 5.1a: Given the data set Paired_t.sav,
use SPSS to calculate the 95% confidence interval of the difference of means of
Sys_BP_1 and Sys_BP_2. Interpret the output.

Problem 5.1b: Given the data set Independent_t.sav,
use SPSS to calculate the 95% confidence interval of the difference of means of
BMI as grouped by gender. Interpret the output.

Problem 5.2: Using the following 2×2 table, calculate
the odds ratio and its 95% confidence interval. Interpret the confidence
interval.

 Exposure to Asbestos Disease yes (Cancer case) Disease no (control) Total Yes 160 80 240 No 20 100 120 Total 180 180 360

Copy and paste (or use the File/Export option in
SPSS) any required data charts or summaries into a Word document, or export the
data output as a Word/RTF document. Save your Application Assignment as a
“.doc”