Chapter 3: Central Tendency Flashcards
What are the three measurers of central tendency?
mean, median, mode
What is a (arithmetic/unweighted) mean ?
The mean is the sum of a set of scores in a distribution, divided by the total number of scores summed.
What is a weighted mean? (MW)
A weighted mean is the combined mean of two or more groups of scores in which the number of scores in each group is disproportionate or unequal.
When is the weighted mean used?
A weighted mean can be used to compute the mean for multiple groups of scores when the size of each group is unequal.
What kind of data is the mean used to describe?
The mean is typically used to describe data that are normally distributed and measures on an interval or ratio scale.
What kind of data is the median used to describe?
The median is typically used to describe data distributions that are skewed and measures on an ordinal scale.
When is the mode used to describe data?
The mode is typically used to describe data with modal distributions and measures on a nominal scale.
What happens to the mean if you change an existing score?
The mean will change
What happens to the mean if you add or remove an existing score?
The mean will change unless that value equals the mean
What happens to the mean if you add/subtract/multiply/divide each existing score by a constant?
The mean will change by that constant
What is the sum of the difference of scores from their mean?
Zero
