Research Methods: measures of central tendency and dispersion Flashcards
Definition of descriptive statistics ?
The use of graphs tables and summary statistics to identify trends and analyse data
Describe measures of statistics ?
The general term for any measures of the average value in a set of data
Describe what it means by the mean ?
The arithmetic average calculated by adding up all the values in a set of data and dividing them by the number of values there are
Describe the median ?
The central value in a set of data when values are arranged from lowest to highest
Describe the mode
The most frequently occurring value in a set of data
What does it mean by bimodal
When there are two modes
Definition of measures of dispersion
General term for any measure of the spread or variation in a set of scores
What does it mean by the range ?
A simple calculation of dispersion in a set of scores which is worked out by subtracting the lowest score from the highest score
Definition of standard deviation ?
A calculation which tells us how much scores deviate from the mean by calculating the difference between the mean and each score
Strength of calculating a mean (central tendency)
Most sensitive measure of central tendency
Includes all the values within calculation
Most representative
Limitation of calculating the mean (extreme values)
Easily distorted by extreme values
Score that is very different from other scores moves mean closer to outlier
Susceptible to skewing
Limitation of calculating a mean (universal measure)
Mean only used with values that represent universal safe measures
Only values that are in seconds , centimetres
Limits which types of data the mean can be used for
Strength of using the median ( extreme values)
Not easily distorted by extreme values
Middle number is not impacted by outlier
Not susceptible to skewing of final calc
Strength of the median (ease)
Easy to calculate
Numbers in order then central value identified
No issues with data analysis
Limitation of median ( sensitivity)
Not as sensitive as mean
Doesn’t include all the values
Not representative of data as whole
Strength of median (universal measures )
Used with values that do not represent a universal measure
Scores from a rating scale
Not limited to which types of data used
Strength of the mode (ease)
Very easy to calculate
Only identify number which occurs the most
No issues with data analysis
Strength of using the mode (nominal data)
Only method that can be used with nominal data
Only way to identify most typical / average value is select models groups
Value of mode is demonstrated
Limitation of mode (crude )
Crude measure
Mode normally very different from mean and mode
Not representative of data as a whole
3 Measures of central tendency
Mean
Median
Mode
2 Measures of dispersion
Range
Standard deviation
What is a strength of the range (ease)
Easy to calculate
Take lowest from highest
No issues with data analysis
Limitation of range (extreme values )
Only takes in account two most extreme values
Unrepresentative of data as a whole
Eg lowest score 0 highest score 100
Range = 100
The smaller the standard deviation the ….
Tighter the dispersion within data spread
What does it mean by tighter dispersion
People are similarly impacted by the IV in an experiment
not a lot of variation between data scores and mean
The larger the standard deviation the ….
Greater the dispersion within data set
What does it mean If dispersion is greater within data
People are impacted differently by an IV in an experiment
Large variation between data scores and the mean
More individual differences
Strength of standard deviation (preciseness )
More precise measurement of dispersion than range
Includes all values within final calc
More representative
Limitations of standard deviation (extreme values)
Easily distorted by extreme values
Score that is very different moves mean closer to outlier
Affects standard deviation
Susceptible to skewing of final calc
