- For population and sample, think about the DATA we're
collecting. The data is quantitative, the number of cavities of elementary
school children.
- The population is number of cavities of all elementary school children in the United States.
- The sample is number of cavities of 1000 elementary school children in the United States (does it say the sample is random?).
- Infer (from Dictionary.com)
1. to derive by reasoning; conclude or judge from premises or evidence: They inferred his displeasure from his cool tone of voice. - Statistics:
- sample mean xbar = 8.84
- sample median = 9
- sample standard deviation s = 1.23
Sample exercise: #3, p. 85
- Samples need to be as large as necessary, but no larger!
- data collection is expensive.
- why collect more than you really need?
- even small samples may be enough: using the Empirical
Rule for some self defense...
- Ice Cream....
- Constructing distributions from data and empirics:
- example data
- Forbes Wealth Data
- We might use the Empirical rule to classify data as outliers
- Figure 4.4, p. 105 and the Empirical Rule
- Percentages in categories
- Percentages over categories
- Practical Example:
Problems A, B of Chapter 4 Example - What do we do with Problem C?
- Z-statistic
- The definition:
- "Z table" (p. 111)
- Deducing/refining the empirical rule
- Using the Z table to do problems:
Problems C, D, E, F of Chapter 4 Example
- The definition: