Key Terms
Five-step process
1. Set up two contradictory hypotheses (H0 and Ha) 2.
Example
H0 = patient is not sick
Use
Normal distribution When: Testing a proportion p Conditions that must all be met:
Degrees of freedom
Df = n - 1
Point estimate
P-prime = x / n (x = number of successes, n = sample size)
Sampling distribution
P-prime ~ N(p, sqrt(pq/n))
Small p-value
Your result is unlikely if H0 is true; evidence against H0 Large p-value: your result is plausible if H0 is true; not en
Memory device
"If the p is low, the null must go. If the p is high, the null must fly."
Claim
50% of first-time brides are younger than their grooms. Sample of 100; 53 said yes.
Distribution
Np = 100(0.5) = 50 > 5; nq = 50 > 5. Use normal.
Compare
Alpha = 0.01 < p-value; do not reject H0.
Conclusion
At the 5% level, there is sufficient evidence that the mean score is greater than 65.
Type I error here
Concluding the time improved when it actually did not. Type II error here: Concluding no improvement when there actually