Chapter 2: Frequency Distributions

Question 1

Frequency Distribution

Answer 1

An organized tabulation showing how many individuals are located in each category on the scale of measurement

Question 2

Frequency Distribution Table

Answer 2

Consists of at least two columns-one listing categories on the scale of measurement (X) and another for frequency (f)

Question 3

Making a Frequency Distribution Table

Answer 3

1. Decide the bins
2. Decide the upper and lower limits of the bins (related to the real limits we discussed in chapter 1)
3. Put your data in the bins

Question 4

Proportions (Relative Frequencies)

Answer 4

Measures the fraction of the total group that is associated with each score
Proportion = p = f/N

Question 5

Percentage

Answer 5

Find the proportion (p) then multiply by 100
Percentage = p(100) = f/n (100)

Question 6

Cumulative Frequencies

Answer 6

The accumulation of individuals as you move up the scale
Adding up the frequencies in and below that category
Cf = (c%/100) (N)

Question 7

Cumulative Percentages

Answer 7

The accumulation of percentages as you move up the scale
The percentage of individuals who are located in and below that category
c% = cf/N (100%)

Question 8

Pecentiles

Answer 8

The percentage of individuals in the distribution with scores at or below the particular value

Question 9

Finding Percentile

Answer 9

1. Go back to the original data
2. Put it in order
3. Use this formula to sort out what data point is in the percentile you want:
   = (c%/100) * (n)
4. Plug it in
   Ex. 50th percentile = (50/100) * 12 = 6
5. Go to that position in the ranked data. (counting from lowest to highest)
   * Round UP to the nearest whole number

Question 10

Class intervals

Answer 10

Groups of scores

Question 11

Grouped Frequency Distribution

Answer 11

Presents groups of scores in a table rather than individual values

Question 12

Rules for creating class intervals

Answer 12

1. Width of the each interval should be relatively simple (ex. 2, 5, 10, 20)
2. The bottom score should be a multiple of the width (ex. Width of 10 points = intervals should start with 10, 20 etc.)
3. All intervals should be the same width

Question 13

What frequency distribution graph to use?

Answer 13

Continuous variables: use histogram or polygon
Discrete variables (not numbers): use a bar graph

Question 14

Histogram vs. Bar graph

Answer 14

Histogram = no spaces between bars (demonstrates they are continuous)
Bar graph = spaces between bars (demonstrates they are separate categories)

Question 15

Symmetrical distribution

Answer 15

it is possible to draw a vertical line through the middle so that one side of the distribution is a mirror image of the other

Question 16

Skewed distribution

Answer 16

the scores pile up toward one end of the scale and taper off gradually at the other end

Question 17

Positive skew

Answer 17

tail on the right

Question 18

Negative skew

Answer 18

tail on the left

Question 19

Tail

Answer 19

the section where the scores taper off

Question 20

Calculating ∑x from frequency distributions

Answer 20

Use all the information from the table (use info in both the f and x columns)
Multiply each x value by its frequency then add the products

Question 21

Calculating the number of rows

Answer 21

rows = highest - lowest +1