Data distribution

Question 1

How will a histogram look with more variation?

Answer 1

Wider histogram

Question 2

What are the 3 distribution skews for histograms?

Answer 2

Negative, positive and normal distribution

Question 3

How will a negative skew look?

Answer 3

Bump to right

Question 4

How will a positive skew look?

Answer 4

Bump to left

Question 5

What do histograms show?

Answer 5

A probability distribution

Question 6

What is the area underneath a histogram equal to?

Answer 6

1, or 100%

Question 7

What are other names for normal distribution?

Answer 7

Gaussian or symmetrical

Question 8

What relationship does a normal histogram distribution show about a variable and the mean?

Answer 8

The distribution of a variable within a population is symmetrical about the mean

Question 9

How do the measures of central tendency look in normal histogram distribution?

Answer 9

Mean = median = mode

Question 10

What s.d. does a small, pointy normal distribution show?

Answer 10

Smaller standard deviation

Question 11

What s.d. does a larger, wider normal distribution show?

Answer 11

Larger standard deviation

Question 12

What must you remember about normal distribution?

Answer 12

For a normal distribution, the proportion of values of a variable within any range can be calculated using the mean and the standard deviation.

Question 13

What must you remember about normal distribution?

Answer 13

For a normal distribution, the proportion of values of a variable within any range can be calculated using the mean and the standard deviation.

Question 14

68% values lie…

Answer 14

+/- 1 standard deviation
from the mean

So 34% is 1 s.d. on one side.

Question 15

95% values lie…

Answer 15

+/- 1.96 standard deviations
from the mean

So 47.5% is 1.96 s.d. on one side.

Question 16

99% values lie…

Answer 16

+/- 2.6 standard deviations
from the mean

So 49.5% is 2.6 s.d. on one side.

Question 17

99.7% values lie…

Answer 17

+/- 3 standard deviations
from the mean

So 49.85% is 3 s.d. on one side.

Question 18

What is the Z-score?

Answer 18

The number of standard deviations a value is away from the mean

Question 19

What can a Z-table tell you?

Answer 19

The proportion of values that are less than X, based on the Z-score calculated using the formula