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Question 1

Frequency Distribution Tables

Answer 1

A frequency distribution is an organized tabulation of the number of individuals
located in each category on the scale of measurement. A frequency distribution can be structured either as a table or as a graph, but in either
case, the distribution presents the same two elements:
1. The set of categories that make up the original measurement scale.
2. A record of the frequency, or number of individuals in each category.

Question 2

Proportions(decimal)- p

Answer 2

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

Question 3

Percentages(%) – p(100)

Answer 3

percentage=p(100)= f/N(100)

Question 4

Group Distribution Tables-intervals 4 guidelines

Answer 4

Used when a set of data covers a wide range of values. The result is called a grouped frequency distribution table because we are presenting groups of scores rather than individual values. The groups, or intervals, are called
class intervals.
1) near 10 intervals
2) simple interval size like 5 or 10
3) bottom score in each class of interval should be multiple of interval size.
4)all intervals same size with no overlap

Question 5

Frequency Distribution Graph

Answer 5

Interval and Ratio Data: Histograms

Polygons

Question 6

Frequency Distribution Graph

Answer 6

Nominal or Ordinal: Bar Graphs (non- number line, IDs, Yelp stars)

Question 7

Population Distributions (relative frequencies)

Answer 7

Unless we know score of entire population,
we must estimate using relative frequencies
Relative frequencies are proportional estimations for given values
When we estimate values, we use a smooth curve to indicate that we do not have exact values

Question 8

Normal Curve

Answer 8

Symmetrical
Bell Shaped
Symmetrical 
Higher frequencies near the mean
Close to zero at the tails
This distribution is used commonly in statistics because it has known frequencies
Sometimes called a “bell curve”

Question 9

Central Tendency (one of three ways to describe a population distribution)

Answer 9

Central Tendency – The “average” of the data (mean, mode, )

Question 10

Variability (one of three ways to describe a population distribution)

Answer 10

How condensed the scores are (spread or narrow)

Question 11

Shape (one of three ways to describe a population distribution)

Answer 11

Symmetrical or Skewed

In a symmetrical distribution, 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.
Skewed distribution- the scores tend to pile up toward one end of the scale and
taper off gradually at the other end
The section where the scores taper off toward one end of a distribution is called the
tail of the distribution.
A skewed distribution with the tail on the right-hand side is positively skewed
because the tail points toward the positive (above-zero) end of the X-axis. If the tail
points to the left, the distribution is negatively skewed

Question 12

Cumulative Frequency

Answer 12

The number of people who score at or below each value. This can be done with a frequency distribution table by simply counting the number of scores that are in or
below each category on the scale.
Start from the bottom-up.
Add the frequencies as you move up
-to eventually determine percentiles/percentile ranks
. The resulting values are called cumulative frequencies
because they represent the accumulation of individuals as you move up the scale.

Question 13

Cumulative Percentage

Answer 13

Convert these frequencies to percentages
c% = (cf/N)(100)
Remember N is the total number of scores so Σf.

They show the percentage of individuals who are accumulated as you move up the scale. (Top value should always be 100%)
Same as Percentiles only when discrete (indivisible) variable

Question 14

Percentiles

Answer 14

The percentile rank is the percentage of scores that fall at or below a given value.(calculate cumulative frequency first for discrete variables)
When you refer to a score by its percentile rank, it is called a percentile

Question 15

Percentile Rank

Answer 15

The rank or percentile rank of a particular score is defined as the percentage of
individuals in the distribution with scores at or below the particular value.

When a score is identified by its percentile rank, the score is called a percentile.

Question 16

Histogram (interval or ratio scale of measurement)

Answer 16

Bars touch

a. The height of the bar corresponds to the frequency for that category.
b. For continuous variables, the width of the bar extends to the real limits of the
category. For discrete variables, each bar extends exactly half the distance to the
adjacent category on each side.

Question 17

Polygon(interval or ratio scale of measurement)

Answer 17

a. A dot is centered above each score so that the vertical position of the dot corresponds to the frequency for the category.
b. A continuous line is drawn from dot to dot to connect the series of dots.
c. The graph is completed by drawing a line down to the X-axis (zero frequency) at
each end of the range of scores. The final lines are usually drawn so that they reach
the X-axis at a point that is one category below the lowest score on the left side and
one category above the highest score on the right side.

Question 18

Bar Graph(ordinal or nominal)

Answer 18

bars do not touch.
A bar graph is essentially the same as a histogram, except that spaces are
left between adjacent bars. For a nominal scale, the space between bars emphasizes that
the scale consists of separate, distinct categories. For ordinal scales, separate bars are used
because you cannot assume that the categories are all the same size.

Question 19

Interpolation

Answer 19

When we can’t find the exact percentiles because of continuous variables.
1Find the width of both intervals
2Locate the position of the known value
3Locate the same position for the unknown value
4Use this position to determine the estimate