Social Statistics Quiz 3 Review

μ

Population mean

σ

Standard deviation of a population

x̄

Sample mean

s

Standard deviation of symbol

Ps

Sample proportion

Pu

Population proportion

Confidence interval using sample means, large samples (N>100), population standard deviation known

c.i. = X̄ ± Z(σ / √N)

Confidence interval using sample means, large samples (N>100), population standard deviation unknown

c.i. = X̄ ± Z(s / √(N − 1))

Confidence interval using sample proportions, large samples (N>100)

Step 1

• Random sampling

• Level of measurement (usually interval/ratio)

• Sampling distribution is normal

Step 2

Null hypothesis (H₀) - always a statement of “no difference”

H₁ - alternative hypothesis

Step 3

Selecting sampling distribution + establish critical region

Over 100 - Z distribution

Alpha (a) = .5 (.1, .01, .001, .0001)

If obtained Z score falls in the CR, reject the H₀

Step 4

Z(obt)

Step 5

• Compare test statistic with the critical region

• If test statistic falls into CR, reject the null hypothesis

• If not, fail to reject hypothesis

One tailed

H₁: μ>7.2

Two tailed

H₁: μ≠7.2

H₁: μ>7.2

CR on right side

H₁: μ<7.2

CR on left side