Normal and skewed distribution

Question 1

Normal distribution

Answer 1

. Most of scores near mean
. Approx 68% scores less than 1 standard deviation away from mean score
. Approx 95% scores less than 2 standard deviations away from mean score
. Approx 99% scores less than 3 standard deviations away from mean score

Question 2

No skew

Answer 2

Mean identical to value at highest peak of distibution curve

Question 3

Positive skew

Answer 3

Long tail on right side of peak , mean value higher than value of score at peak of distribution curve

Question 4

Negative skew

Answer 4

Long tail on left sode of peak, mean value lower than value of score at peak of distribution curve

Question 5

Standard deviation

Answer 5

Measure of dispersion that tells us amount by which score within set of scores varies from mean and thus how tightly scores cluster around mean. Tight = small SD, wide = large SD

Question 6

Standard deviation of population formula

Answer 6

standard deviation= square root of sum of scores(each value in population-mean)squared divided by no of scores

Question 7

Standard deviation of sample formula

Answer 7

Standard deviation= square root of sum of scores(value-mean)squared divided by no of scores in sample-1

Question 8

Variance

Answer 8

Measure of dispersion and is a mathematical expression of how scores are spread across data set. Mean of squares of distance each score in set data is from mean