1. & STATISTICAL SAMPLING
Nevada Math Project
ISSUES IN PROBABILITY
& STATISTICAL SAMPLING

2. WHAT DO PEOPLE THINK?
How Tall are Dragons?
HOW BIG ARE STARS?

3. But you can’t ask everyone!
You have a Question!
But you can’t ask everyone!
SO YOU NEED A SAMPLE!

4. NO BIAS PLEASE!

5. So you take a random sample and compute statistics about it.
You hope it reflects information
about the entire population!
SO YOU NEED
A RANDOM
SAMPLE
SO YOU AVOID BIAS

7. RANDOM
NUMBERS
ARE THE
KEY

8. Stratified Random Sample

9. USUALLY SAMPLES ARE REPRESENTAIVE
BUT OCCASIONALLY ….
CHAOS

10. MEAN ABSOLUTE DEVIATION
MAD & MEDAD
MEAN ABSOLUTE DEVIATION
DATA EXAMPLE: {2,14,2,4,3}
DO BOX PLOT
2 𝑸 𝟏 = 𝟐+𝟐 𝟐 =𝟐 2 𝑸 𝟐 =𝟑 4 𝑸 𝟑 = 𝟒+𝟏𝟒 𝟐 =𝟗 14 14 9 2 3

11. MEAN ABSOLUTE DEVIATION
MAD & MEDAD
MEAN ABSOLUTE DEVIATION
DATA EXAMPLE: {2,14,2,4,3}
Find mean, median, mode,
standard deviation, MAD

12. STANDARD DEVIATION DATA EXAMPLE: {2,14,2,4,3} Standard Deviation
MEAN = 5 so Variance is the average of
(2−5) 2 =9 (Count this twice)
(4−5) 2 =1
(3−5) 2 =4
(14−5) 2 =81
The Variance = = =20.8
Standard Deviation
= 𝟐𝟎.𝟖 ≈𝟒.𝟓𝟔