measures of central tendency + dispersion Flashcards
(25 cards)
What are descriptive statistics?
The use of graphs, tables, and summary statistics to identify trends and analyze sets of data.
What are measures of central tendency?
The general term for any measure of the average value in a set of data.
What is the mean?
The arithmetic average calculated by adding up all the values in a set of data and dividing by the number of values.
What is the median?
The central value in a set of data when values are arranged from lowest to highest.
What is the mode?
The most frequently occurring value in a set of data.
What are measures of dispersion?
The general term for any measure of the spread or variation in a set of scores.
What is the range?
A simple calculation of the dispersion in a set of scores, worked out by subtracting the lowest score from the highest score and adding 1 as a mathematical correction.
What is standard deviation?
A sophisticated measure of dispersion in a set of scores. It tells us by how much, on average, each score deviates from the mean.
How do you calculate the mean?
Add up all the scores and divide by the total number of scores.
How do you calculate the median?
Arrange the scores in order and select the middle value. If there is an even number, take the mean of the two central values.
How do you calculate the mode?
Identify the value that occurs most frequently in the data set.
How do you calculate the range?
Subtract the lowest score from the highest score and add 1.
What does a high standard deviation indicate?
Scores are widely spread out from the mean.
What does a low standard deviation indicate?
Scores are closely clustered around the mean.
What is a bi-modal data set?
A data set that has two modes (two values that occur most frequently).
Why is the mean considered representative?
Because it includes all scores in the calculation, making it more representative of the data set as a whole.
What is a disadvantage of the mean?
It can be distorted by extreme values (outliers).
What is an advantage of the median?
It is not affected by extreme scores and is useful for skewed distributions.
What is a disadvantage of the median?
It ignores the values of lower and higher numbers except for their position.
What is an advantage of the mode?
It is the only measure that can be used with nominal data.
What is a disadvantage of the mode?
There may be more than one mode or no mode at all.
What does the range take into account?
Only the highest and lowest values, not the distribution of the rest of the data.
What is a disadvantage of the range?
It can be distorted by extreme values and does not reflect the overall distribution.
What is the formula for standard deviation (in words)?
The square root of the sum of squared differences between each score and the mean, divided by the number of scores minus one.
