Inferential Statistics

Question 1

Postive skew

Answer 1

Skewed to the right
Bulk of scores at the lower end
Mean to the right of peak

Question 2

Negative skew

Answer 2

Skewed to the left
Bulk of scores to the higher end
Mean to the left of peak

Question 3

Normal distribution

Answer 3

Scores equally spread around the mean

Mean roughly in the middle of the peak

Question 4

68-95-99.7 rule

Answer 4

When scores are normally distributed most scores will be spread within 3 SD of the mean
68% within 1 SD
95% within 2 (1.96) SD
99.7% within 3 SD

Question 5

Why 95% confidence interval?

Answer 5

Compromise between being as certain as possible and keeping the interval as small as possible