Distributions and Variance

Question 1

Skew

Answer 1

the symmetry of the distribution

Question 2

Positive skew

Answer 2

scores bunched at low values with the tail pointing to the high values

Question 3

Negative skew

Answer 3

scores bunched at high values with the tail pointing to the low values

Question 4

Sum of squares

Answer 4

• determines the dispersion of data points

- a.k.a. variance

Question 5

Calculating sum of squares

Answer 5

1. count the number of measurements (n)
2. calculate the mean
3. square the difference of each measurement from the mean
4. add the squares and divide by (n-1)

Question 6

Standard deviation

Answer 6

how much the members of a group differ from the mean value for the group

Question 7

Calculating standard deviation

Answer 7

Square the sum of squares

Question 8

Degrees of freedom

Answer 8

the number of independent values or quantities which can be assigned to a statistical distribution

Question 9

Calculating degrees of freedom

Answer 9

n - (number of parameters estimated from the data)

usually df = n - 1

Question 10

Calculating variance

Answer 10

(sum of squares)/(degrees of freedom)