PSYC*1010 Chapter 3: Central Tendency Flashcards
What is central tendency?
A statistical measure to determine a single score that defines the centre of a distribution
What is the goal of calculating a central tendency?
To find a single score that is most representative of the entire group
Which statistical measure is useful for making comparisons between sets of scores?
Central tendency
What are the three measures of central tendency
- Mean
- Median
- Mode
What is the preferred measure of central tendency?
Mean
How is mean calculated?
By computing the sum of scores and dividing it by the total number of scores
T or F: Changing the value of any score will change the mean.
True
When will adding or removing a score for the distribution NOT change the mean?
When the new or removed score is the same as the mean
What will happen to the mean is a constant value is added, subtracted, multiplied or divided to/from/by every score in a distribution?
The mean will change in the same way
What does μ represent?
The population mean
What do M and X̅ represent?
The sample mean
What two values are needed to calculate weighted mean?
- The overall sum of scores for the combined group
- The total number of scores in a combined group
How is mean calculated from a frequency distribution table?
Multiply each score (X) by its frequency and divide the product by the total number of score (Σf)
What is the median?
The midpoint of scores in a distribution when they are listed in numerical order
How is the median calculated when the number of scores is even?
When the number of scores is even, the median is found by computing the average of the two centre scores
Which measure of central tendency is best when extreme scores or skewed distributions are present?
Median
Which measure of central tendency should be used if an undetermined score is present?
Median
Which measure of central tendency should be used if there is an open-ended distribution/ no upper limit?
Median
Which measure of central tendency should be used if scores are measured on an ordinal scale?
Median
What is the mode?
The score or category with the greatest frequency
Which measure of central tendency corresponds to an actual score in the data?
Mode
What is a bimodal distribution?
A distribution with two modes
What does a bimodal distribution indicate?
That two separate and distinct groups of individuals exist within the sample/population
What is a multimodal distribution?
A distribution with more than two modes
When is the term “major mode” used?
Used casually to refer to the taller peak of two modes that are unequal yet have distinctly high frequencies
When is the term “minor mode” used?
Used casually to refer to the smaller peak of two modes that are unequal yet have distinctly high frequencies
Which measure of central tendency should be used if scores are measured on a nominal scale?
Mode
Which measure of central tendency is best when variables are discrete?
Mode
T or F: Modes are rarely, if ever, shown in a graph.
True
What is the main determining factor when deciding how means and medians will be presented?
The scale of measurement used for the independent variable
Where are the mean, median, and mode located in a symmetrical distribution?
Exactly at the centre
Where are the mean, median, and mode located in a rectangular distribution?
- Mean and median are exactly at the centre
- There is no mode
Where are the mean, median, and mode located in a positively skewed distribution?
In order from left to right: mode (at the peak), median, then mean
Where are the mean, median, and mode located in a negatively skewed distribution?
The measures of central tendency are presented in order from left to right as mean, median, then mode (at the peak)
