PAPER 2 - Research Methods - Measures of central tendency and dispersion Flashcards
What are descriptive statistics?
The use of graphs, tables, and summary statistics to identify trends and analyse sets of data.
What are measures of central tendency? (MoCT)
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 occuring value in a set of data.
What are measures of dispersion? (MoD)
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 which is worked out by subtracting the lowest score from the highest score and adding 1 as a mathematical correction.
What is the 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.
Evaluate the mean as a MoCT.
Most sensitive measure of central tendency as it includes all the scores/values in the data set within the calculation = more representative of the data.
It is easily distorted by extreme values so may not represent data overall.
Evaluate the median as a MoCT.
Extreme scores do not affect it.
It is easy to calculate.
Less sensitive than the mean as actual values of lower and higher numbers are ignored and extreme values may be important!
Evaluate the mode as MoCT.
Easy to calculate.
For some data i.e. data in categories, the mode is the only MoCT you can use…modal group!
Not representative of the whole data set.
Several modes = not a very useful pice of information.
Evaluate the range as a MoD.
Easy to calculate.
Only takes into account the two most extreme values…unrepresentative of all the data.
May not give a fair representation of the general distribution of data…influenced by outliers.
Doesn’t indicate whether most numbers are closely grouped around the mean or spread out.
Evaluate standard dispersion as a MoD.
Precise MoD as it includes all values within the final calculation.
Can be distorted by a single extreme value.
Extreme values may not be revealed but may be important.
