Measures of Central Tendency Flashcards
What is a measure of location?
a single value which describes a position in a data set
What is a measure of central tendecy?
a single value that describes the centre of the data
What is the mode or modal class?
The value of class that occurs most often
What is the median?
The middle value when the data values are put in order
Formula to calculate mean
x̄ = Σx
—-
n
what does x̄ represent?
the mean of the data
what does Σ represent?
the sum of the data values
What does n represent
the number of data values
Formula for data given in frequency table
Σxf
x̄ = —–
Σf
What does Σxf represent?
the sum of the products of the data values and their frequencies
What does Σf represent?
The sum of the frequencies
Mode
this is used when data is qualitative or quantitative with either a single mode or two modes (bimodal). it is not very informative if each value occurs only once
Median
This is used for quantitative data. it is usually used when there are extreme values, as they do not affect it
Median
This is used for quantitative data. it is usually used when there are extreme values, as they do not affect it
Mean
This is used for quantitative data and uses all the pieces of data. it therefore gives a true measure of the data. however it is affected by extreme values
