PSY 511: Z TEST AND T TEST

ONE SAMPLE Z TEST

NULL and ALTERNATIVE HYPOTHESIS: (testing if the person is younger)

H₀: μ x̄ > or = 40 (The average age in his company is not younger than the norm.)

HA: μ x̄ < 40

(The average age in his company is younger than the norm.)

NULL and ALTERNATIVE HYPOTHESIS: (testing if the person is older)

H₀: μ x̄ ≤ 40
(The average age in his company is NOT older than the norm.)

H₁: μ x̄ > 40

(The average age in his company is older than the norm.)

Mean

xˉ=Σx​

—-

N

Standard Error of Mean

o= SD from the prompt

u= average/ mean from prompt

Z test Calcuation

Interpreting the findings (significant)

z= -1.79 , p < 0.05 (our number is better then p)

(our number falls in grey area)

Interpreting the findings (NOT significant)

z = -1.79, p > 0.05 (our number is not significant to p )

Z TEST 2 TAILED

NULL AND ALT HYPOTHESIS

H0​:μ x̄ =6(no difference between the population mean and 6)

HA:μx̄ ≠6(the population mean is different from 6)

Type I Error

• If p < α → Reject H₀

Type II Error

• If p > α → Fail to reject H₀

T- TESTS

Null and Alternative Hypothesis

H0​:μ x̄ =69.5 (the average math score is not different from the norm)

HA:μx̄ ≠69.5 (the average math score is different from the norm)

Standard Error of Mean

T calc Score

Interpretation Written Statement (SIGNIFICANTLY HIGHER)

(t(9) = + 4.00, p < 0.01)