Descriptive Statistics

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What do you do with the data from your research?

• Present it visually– bar graphs, histographs

• Organize, summarize, and make inferences

What type of descriptive statistics are illustrated on the page?

Summarizing data use:

• Measures of Central Tendency– Mode- most frequent score– Mean- average of the scores– Median- the middle score

Important to ALWAYS check the range or scale of the graph. See book page 40 and 41

What type of Central Tendencies are used in each example?

• Measures of VariationThe amount of variation within data field– Range- low to high score

• Not so accurate

– Standard Deviation- how one score varies around the mean score

• Most accurate

Which Measure of Variation is used in these examples?

How do I know that any difference is reliable?

• Know what population is sampled

• Look for consistency

• More population the better

How do I know if there is a Statistical Difference?

• Are the sample averages reliable?

• Is the difference between them relatively large?

• Does it indicate the likelihood that the result happened by chance?

• Remember- that it does not indicate the importance of the result

Lab Assignment

• Find a graph in a current magazine or newspaper.• Analyze it and look for:

– How the ad is used (purpose)?

– What statistics are used to make a point?

– Who did the research?

– What other features are used to influence the reader?

– Type your answer and turn it in at your next class meeting.