Chapter 4 Main ideas

Question 1

different ways to measure variability

Answer 1

Range: Highest score - lowest score. A rough measure of variability.

Variance

Standard Deviation

Question 2

what is variance

Answer 2

The variance is the standard deviation squared. It’s hard to interpret/ conceptualize b/c it is in squared units. If you take the square root, you will have the standard deviation.

Question 3

what is the standard deviation

Answer 3

The average amount of that the scores in your sample deviate (differ) from the mean.
The larger the SD, the more spread out the scores in your sample.
SD of 0 would mean that every score is the same.

Question 4

why is n-1 in the demoniator for sample variance

Answer 4

When n – 1 is used instead of n is the denominator of the formulas results in a slightly higher estimate of variability, (N - 1) has less and less of an impact on the final product of the formula as the N becomes larger.

Question 5

what percentage of scores fall within one SD of the mean, 2 SD of the mean and 3 SD of the mean?

Answer 5

68%, 95%, 99.7%

Question 6

which has more variability samples or populations

Answer 6

populations

Question 7

What does variability show us?

Answer 7

how spread out a distribution is and how accurately the mean describes the distribution