1. Therefore, the Age variable is a categorical variable.
In a study, the age information was collected in terms of the following age categories.
Therefore, the Age variable is a categorical variable.
AGE
Percentage
20 to less than 30
23%
30 to less than 40
30%
40 to less than 50
35%
50 to less than 60
10%
60 and above 2%
Yes or No

2. There is significant correlation between treatment and outcome.
Observational study: results from 2 treatment levels (different dosages) and their outcomes. (Data from 200 randomly selected patients.)
Hypertension
Treatment
Yes No
Total
A: 250mg 44 56
100
B: 500mg 29 71 73
127
200
Treatment A: 44/100 = 44%
Treatment B: 29/100 = 29%
There is significant correlation between treatment and outcome.

3. So, lower dosage was the cause of the higher rate of hypertension.
Your Answer:
Yes or No
Association does not imply causation

4. Hypertension Below 65 65+ Treatment Yes No Total A 5 18 23 39 38 77 B
Multivariate approach in data analysis
Hypertension
Below 65
65+
Treatment
Yes No
Total A 5 18 23 39 38 77 B 17 60 12 11
* Older patients prefer Drug A
OR <65: A: /23 = 22%
B: 17/77 = 22%
OR 65+: A: 39/77 = 51%
B: 12/23 = 52%

5. Two Quantitative variables
Average annual temperature and the mortality index for breast cancer in women in certain region of Europe.

6. Since there is very clear upward linear trend, so can we conclude that the high temperature increased the mortality index?
Your Answer:
Yes or No

8. When a person’s height is 45 inches, the expected weight for the person’s would be around 40 lbs.
Yes or No

10. Confidence interval with z-score:
The (1 a)% confidence interval estimate for population mean:
Assumption: If sampled from normal population with known variance, s, 
Assumption: If large sample and if unknown variance, s replaces s,
Rarely used in practice!

11. “The” Method Used in Practice
Confidence interval with t-score:
The (1 a)% confidence interval estimate for population mean:
Assumption: If sampled from normal population with unknown variance, s, 
(If sample size is large the normality assumption is insignificant.)
t  z as sample becomes large

12. t-Test Statistic for testing Mean
p-value is the common approach

13. Student’s t DistributionZ
Standard Normal (Z)
Bell-Shaped
Symmetric
‘Fatter’ Tails
t (df = 13)
t (df = 5) t