| A | B |
|---|
| Five reasons for organizing data into frequency | 1. organize the data in a meaningful, intelligible way; 2. to enable the reader to determine the nature or shape of the distribution; 3. to facilitate computational procedures for measures of average and spread; 4. to enable the researcher to draw charts and graphs for the presentation of data; 5. to enable the researcher to draw charts and graphs for the presentation of data; 5. to enable the reader to make comparisons among different data sets |
| three types of frequency distributions, and explain when each should be used | categorical frequency distribution, grouped frequency distribution, cumulative frequency distribution; |
| categorical frequency distribution | is used for data that can be placed in specific categories, such as nomicnal-or ordinal-level data. |
| political afiliation, religious affiliation, major field of study | would use categorical frequency distribution |
| cumulative frequency distribution | are used to show how many data values are accumulated up to and including a specific class; a way to list how many values fit into the first class, the first 2 classes, the first 3 classes, etc., or the last class, the last 2 classes, etc. |
| grouped frequency distribution | used when the classes contain more than one data value; used when the range of data is large and the data must be grouped into classes that are more than one unit in width |
| anybody who is 65 or older | open-ended frequency distribution |
| distribution of number of hours that boat batteries lasted | grouped freqency distribution |
| How many classes should frequency distributions have? | Usually 5 to 20 classes are used, but in any case, make sure that you use enough classes to give a good description of the data. |
| Why should the class width be an odd number? | This ensures that the midpoint of each class has the same place value as the data. This will guarantee that the class midpoints are integers instead of decimals. |
| What are open-ended frequency distributions? | a frequencu distribution that has no specific beginning value or no specific ending value |
| Why are opened-ended frequency distributions necessary? | ..used when the classes are not equal in width |
| the total record high temperatures are less thatn or equal to 114 degrees; 48 of the total record high temperatures are less than or equal to 124 degrees. | cumulative frequency examples |
| ungrouped frequency distribution | when the range of the data values is relatively small and a frequency can be constructed using single data values for each class |
