7. Percentage of Specimens Testing
Positive for RSV
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
South 2 2 5 7 20 30 15 20 15 8 4 3
North- 2 3 5 3 12 28 22 28 22 20 10 9
east
West 2 2 3 3 5 8 25 27 25 22 15 12
Mid- 2 2 3 2 4 12 12 12 10 19 15 8
west
8. Descriptive Statistics
Percentage of Specimens Testing Postive for
RSV 1998-99
35
30
25 South
20 Northeast
15 West
10 Midwest
5
0
Jul Sep Nov Jan Mar May Jul
9. Describing the Data
with Numbers
Measures of Central Tendency
⢠MEAN -- average
⢠MEDIAN -- middle value
⢠MODE -- most frequently observed
value(s)
10. Distribution of Course Grades
14
12
10
Number of 8
Students 6
4
2
0
A A- B+ B B- C+ C C- D+ D D- F
Grade
11. Describing the Data
with Numbers
Measures of Dispersion
⢠RANGE
⢠STANDARD DEVIATION
⢠SKEWNESS
12. Measures of Dispersion
⢠RANGE
⢠highest to lowest values
⢠STANDARD DEVIATION
⢠how closely do values cluster around the
mean value
⢠SKEWNESS
⢠refers to symmetry of curve
13. Measures of Dispersion
⢠RANGE
⢠highest to lowest values
⢠STANDARD DEVIATION
⢠how closely do values cluster around the
mean value
⢠SKEWNESS
⢠refers to symmetry of curve
15. Measures of Dispersion
⢠RANGE
⢠highest to lowest values
⢠STANDARD DEVIATION
⢠how closely do values cluster around the
mean value
⢠SKEWNESS
⢠refers to symmetry of curve
16. Skewness
Curve A Curve B
Mode
Median
negative
skew
Mean
17. The Normal Distribution
.
Mean = median =
mode
Mean, Median, Mode
Skew is zero
68% of values fall
between 1 SD
95% of values fall
between 2 SDs
1 2Ď
Ď