Statistics Chapter 2 - Tabular and Graphical Methods

• Frequency Distribution
• Relative frequency distribution
• Bar graph
• Pie Chart

• Nominal
• Ordinal

• Frequency distribution 
• Relative frequency distribution
• Histogram
• Cumulative distributions

• Interval
• Ratio

5-20

(largest data value - Smallest data value) / Number of classes

• The value halfway between the lower and upper class limits
• Example: 10-14 (12)

• Classes can not overlap
• Classes can not have breaks
• Each data item must fit into only ONE class
• Classes must have the same width

A frequency distribution class that requires only a lower class limit or an upper class limit.

Near perfect bell curve

Longer tail to the left on a histogram.

Longer tail to the right.

A histogram has no spaces between each bar.

Each value represents the frequency of the current class plus the amounts of all previous classes.

• Tabular summary of 2 variables
• The variables can be qualitative or quantitative

• Row
• Columns

Conclusions based on aggregated data may be reversed when we look at unaggregated data.

• Both values on the x and y axis are increasing
• They have a correlation

• When x increases, y decreases.
• There is still a correlation

The y value has no correlation to x.