Chapter 4- Central Tendency and Variability Flashcards
What is the central tendency?
Central tendency is the -one of the mot important ways to to understand a distribution of data–typical score. It is the highest point on the histogram or the polygon. The mean, median, and mode as an indicator of central tendency.
What is the mean?
The mean is the arithmetic average of a group of scores, the typical score in a distribution. The mean is a visual point that perfectly balances two sides of a distribution.
How is the mean calculated?
The mean is calculated by summing all of the scores in a data set then dividing this sum by the total number of scores.
What symbol is used for the mean?
M
What is the median?
The median is the middle score of all the scores in a sample when the scores are arranged in ascending order.
How is the median score calculated?
The median is calculated by lining up all the scores in ascending order and find the score that falls in the middle of all the scores. If there is a odd number of scores, there will be an actual middle score; if there is an even number of scores, there will be no actual middle score. When this happens, take the mean of the two middle scores. Best to use median when data has outliers (extreme scores) and when data is skewed
What is the mode?
The mode is the most common score.of all score in the sample. It occurs most frequently. Usually used for nominal data (ex. eye color, hair, ect)
What is variability?
Variability is the numerical way of describing how much spread there is in a variability.
What are three measures of variability?
Three measure of variability are range, variance, and standard deviation.
What is the range?
The range is a measure of variability calculated by subtracting the lowest score (the minimum) from the highest score (the maximum)
What is unimodal?
Unimodal is when a distribution of cores has one mode. (one peak)
What is bimodal?
Bimodal is when a distribution has two modes (two peaks)
What is multimodal?
Multimodal is when a distribution has more than two modes (many peaks)
What is variance?
Variance is the average of the squared deviations from the mean–variability
What is a standard deviation?
A standard deviation the square root of the average of the squared deviations from the mean, and is the typical amount that each score varies, or deviates from the mean
