1. Review of Descriptive Statistics
CE 308
Civil Engineering Synthesis I

3. RELATIVE Frequency
Frequency / total observations, n

4. f(x) 1 2 3 4 x

5. f(x) + 1 2 3 4 x

6. f(x) + 1 2 3 4 x

7. CDF 1
pdf

8. CDF = Cumulative Distribution Function
F(x)
p(X < x) non-exceedence
pdf = Probability Distribution Function
f(x)
p(X = x)

9. Probability
Non-Exceedence Probability
Exceedence Probability

10. Mean, x

11. Measures of Central Tendency
Mean
Center of gravity
Median
Half the values of x are smaller
and half are larger
Mode
Value of x with the largest frequency

12. Mean, x
WHY
(x-x)2

13. Non-Symmetric
Symmetric

14. Negative Skew

15. Positive Skew

16. Normal

17. Normal Distribution