Chapter 2 - Measures of location and spread Flashcards
What is a measure of location?
Single values which describe a position in a data set
What is a measure of central tendency?
A single value representing the centre of the data
What is a measure of spread?
How data is spread out
How to use a calculator to find measures of central tendency?
Menu 6 - statistics 1 - variable Fill in table and frequency Press AC Press option Press 2
When will the mode be the best measure to use?
When the data is qualitative, or quantitative with a single mode
When will the median be the best measure to use?
Quantitative data with extremes
When will the mean be the best measure to use?
No extreme values in quantitative data
Formula for the mean
Sum of data values / number of data values
Formula for the mean from a frequency table
Sum of the products of data values and their frequencies/sum of the frequencies
What is the lower quartile?
A quarter of the way through the data set
What is the upper quartile?
Three quarters of the way through the data set
How do you find the lower quartile for some data?
(N+1) / 4
How do you estimate the mean, quartiles and percentiles using grouped data?
Interpolation
What are the formulae for standard deviation and variance?
See flashcards
What is the interquartile range?
The difference between the upper and lower quartiles
