Activity 2 – Descriptive Statistics

1. A cumulative relative frequency distribution

a) expresses the same information as a frequency distribution, but in a different way b) gives the probability that a variable is less than or equal to a particular value c) always takes on a value between zero and one d) all of the above e) none of the above Changed d) and e)

2. A relative frequency distribution may be obtained by dividing the frequencies by the total number of observations.

True False

3. The relative frequencies in a relative frequency distribution should add to one.

True False

4. Identify each variable type:

Variable Scale a) Geographic region (N,S,E,W) 1. Nominal 2. Ordinal 3. Count/Measurement b) Daily stress level 1. Nominal (Low, Moderate, Severe) 2. Ordinal 3. Count/Measurement c) Years of education 1. Nominal 2. Ordinal 3. Count/Measurement d) Body temperature 1. Nominal 2. Ordinal 3. Count/Measurement e) Class status 1. Nominal (fresh, soph, jr, sr) 2. Ordinal 3. Count/Measurement f) Serum glucose in mg/dl 1. Nominal 2. Ordinal 3. Count/Measurement g) Race 1. Nominal 2. Ordinal 3. Count/Measurement

5. Match graphs to variables [Activity-based Statistics].

6. Match statistics to graphs [Activity-based Statistics].

The summary statistics for the variables age01 (age in years), gend01 (gender, 0=female, 1=male), serum cholesterol (chol44), blocks walked per week (block04), stht13 (standing height in cm), weight13 (weight in lbs.), race01 (race, 1=white, 2=black, 3=other) and associated figures were created in Stata. Answer the questions that follow.

Variable | Obs Mean Std. Dev. Min Max ------+------age01 | 9908 72.40101 5.49398 65 100 gend01 | 990 .408080810 .4917267 0 1 chol44 | 990 208.657612 37.4204 (91 351)9 block04 | 973 43.291887,13 56.4910 0 300 stht13 | 989 165.8542 9.33933 141.5 196 weight13 | 989 156.779 32.78357 76 323

RACE | Freq. Percent Cum. ------+------1.00 | 893 90.20 90.20 2.00 | 92 9.2911 99.49 3.00 | 4 0.5011 100.00 ------+------Total | 990 100.00

PERCENTILES Variable 25% 50% 75% ------chol44 183 20612 231 block04 6 2413 60

7. The average number of blocks walked per week was 43.3.

8. The sample size for these data was 990

9. The range for cholesterol was (91, 351).

10. Approximately 59.2 % of the sample was female.

11. The percentage of non-white subjects in the sample was 9.8

12. The mean and median cholesterol levels are 208.7 and 206.

13. The mean and median blocks walked per week are 43.3 and 24 .

14. The histogram for cholesterol seems to show that the cholesterol levels are

a) negatively skewed b) symmetric c) positively skewed

15. The histogram for blocks walked per week shows the variable is

a) negatively skewed b) symmetric c) positively skewed

Histogram for cholesterol level

0 . 2 0

0 . 1 5

0 . 1 0

0 . 0 5

0 . 0 0 1 0 0 . 0 0 2 0 0 . 0 0 3 0 0 . 0 0 4 0 0 . 0 0 C H O L E S T E R O L

Histogram for blocks walked per week

0.60

0.40

0.20

0.00 0.00 100.00 200.00 300.00 BLOCKS WALKED/WEEK