CHAP 10 :Estimation
- 2 types of estimators: Point Estimator & Interval Estimator.
- Estimation the population mean when variance is known: = ẍ ± [Z α/2 ./ √n]
- Population standard deviation (∂) larger - the larger the confidence interval;
The confidence level (1-α) larger - the larger the confidence interval.
The sample size (n) increasing - decreases the confidence interval; if (n) = population size -> conf. level is single #
- Selecting sample size: n = [ (Z α/2. ∂)/B] B: b/w or within. N= 238.1 -> n = 239 (always round it up)
CHAP 11 :Introduction to Hypothesis Testing
- Prove sth does or doesn't exist.
- Hypothesis: H :0the mull hypothesis; H : a1ternative hypothesis.
- E.g: Hypothesis: Ho: u = 36; H : 1 < 36; Test Stat: z = (ẍ-M)/ (б/√n)=(34.25-36)/(8/√12)= -.76; Rejection: z < −z = −z. α 05
= -1.645; P-Value: P(Z < -.76) = .2236. Conclusion: Do Not Reject Ho. There is not enough evidence to infer that the
average student spent less time than recommended.
- Calculating the Probability of a type 2 error: type 1 (α); type 2 (calculating process)
If type 2 error is judged too large, we can :increase α, or increasing sample size.
CHAP 12: Inference about once Population
Inference About a Population Mean
- When ∂ unknown: s =[ ∑x -(∑x) /n]/(n-1); estimate: ẍ ± t s/√n
Inference About a Population Variance
- When ∂ known: c