Frequency distributions

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# Frequency distributions

## Frequency distributions

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##### Presentation Transcript

1. Frequency distributions Chapter 2

2. What are frequency distributions? • Table or graph that lets you quickly and easily see how many responses of a particular value (or range of values) you have

3. Why do we care? • Lets you quickly and easily see if you have invalid values • Lets you quickly and easily see where participants are • Consistent with who recruited – e.g., if newlyweds, should have high levels of satisfaction, and short levels of length of marriage

4. Table • One column has possible values of variable, grouped or ungrouped • Another has number of people with that value (or range of values) • Another may have percentage or proportion of people with that value (or range of values)

5. Graphs • Regardless of type of frequency distribution graph: • Value of variable on X axis • Frequency of that value on Y axis

6. Histogram • Used for quantitative variable • Bar for each possible value of variable • No space between bars • Height of bar = number of people with that value

7. Bar graph • Same idea as histogram, but used for qualitative variables • To reinforce this, space between bars on graph

8. Polygon • Think of shape – created from dots and connecting lines • Dot placed at height corresponding to number of people with a particular value • Repeated for each possible value • Dots connected

9. Types of distributions • Symmetrical • Skewed • Positive/to the right • Negative/to the left • Named by where the tail is