AP Psychology - 1.6

Descriptive Stats - summarize/describe numerical data

• Measures all the subjects and summary data is certain

Inferential Stats - numerical data that allows one to generalize; estimates based on sample data

Low variable observations are more reliable than those that are more variable

Correlation Data

• The pattern of dots on a scatterplot allows one to determine if a relationship exists between two variables

Correlation coefficient - a numerical measure of the strength of two variables; falls somewhere between -1 and 1, with 0 being No Correlation

• A larger sample size helps to ensure that the observed effect did not occur simply due to a sampling a error

  • Replicated data also ensures results are accurate (not a fluke)

 Measures of Central Tendency

Mean - the arithmetic average (sum total of all scores divided by the number of scores)

Median - the midpoint/halfway point in a date set (50th percentile)

Note: Remember that on a highway, the median is the middle… half way below it

Mode - the most frequently occurring score or scores in a data set

Skewed - a representation of scores that is lopsided due to a few way-out scores

Regression toward the mean - As more data is collected, the chance that random factors could influence the data is reduced

Measures of Variation

Range - the difference between the lowest and highest scores in a distribution

Standard deviation - the amount of variation in relation to the mean score

Normal Curve - bell-shaped curve that represents a normal distribution of scores