WHSAP Psychology

Descriptive Statistics:Scales of Measurement

Measures of Central Tendency

I CAN Answer

• How do psychologists draw appropriate conclusions about behavior from research?

Statistical ReasoningStatistical procedures analyze and

interpret data and let us see what the unaided eye misses.

White63%

Black16%Hispanic

10%Asian7%

Others4%

Composition of ethnicity in urban locales

Describing Data

Meaningful description of data is important in research. Misrepresentation

can lead to incorrect conclusions.

Central Tendency

• Tendency of scores to congregate around some middle variable

• A measure of central tendency identifies what is average or typical in a data set

Measures of Central Tendency

Mode: The most frequently occurring score in a distribution.

Mean: The arithmetic average of scores in a distribution obtained by adding the scores and then dividing by their number.

Median: The middle score in a rank-ordered distribution.

But the mean doesn’t work in a skewed distribution

The Median is much better

Negatively Skewed

                

Positively Skewed

CAN I ANSWER

• How do psychologists draw appropriate conclusions about behavior from research?