Descriptive Stats

3 characteristics to Organize and Describe data sets

1. Center

2. Shape

3. Variability

Frequency Distribution table

shows classes or intervals of data with a count of entries

frequency

number of data entries

Lower Class limit

smallest number that can be in a class

Upper class limit

largest number that can be in a class

range

difference between the max and min number of a data set

Steps to construct a frequency distribution table

1. find width

2. find limits

3. tally for the frequency

4. Relative frequency

5. Cumulative frequency

6. Midpoints

7. boundaries

Class width formula

range/ number of formulas

midpoint formula

(Lower class limit) + (upper class limit) / 2

Relative frequency formula

class frequency / sample size

Cumulative frequency

sum of the frequencies of that class and previous class

frequency histogram

uses bars to represent frequency distribution of a data set

frequency histogram properties:

1. Horizontal scale is qualitative and measures data

2. Vertical scale measures frequencies of the classes

3. bars must touch