t-test

Question 1

t-test

Answer 1

Test used to measure whether two groups differe significantly by comparing the means
H0; No significant difference (distriution centered on 0)
H1: Significant difference

Two-tailed: direction of effect not specified, reject H0 if p<.05
One-tailed: when the direction of effect is mentioned. First; check if effect is in right direction, if so: p:2

Question 2

Calculating the t-stat

Answer 2

t = Mean(x) - mean(y) / SE (Mean(x) - mean(y) )

Question 3

SD and SE

Answer 3

Standard deviation gives the spread of data around the mean

Standar error gives the spread of data around the overall mean. If you would do the test again and again, what the spread would be.
- Calculated by deviding the SD by the sq rt of the N

Question 4

Assumptions

Answer 4

1. Independence
2. Normality
3. Homogeneity