Measures of Central Tendency and Dispersion Flashcards
what are the measures of central tendency?
- mean
- median
- mode
what is the mean?
allows us to recognise the average
what are the strengths of the mean?
- most sensitive of the measures of central tendency(includes all values)
- more representative of the data as a whole
what are the weaknesses of the mean?
- mean is easily distorted by extreme values
what is the median?
middle value in a data set when scores are arranged from highest to lowest
what are strengths of the median?
- extreme scores don’t affect it
- easy to calculate
what are weaknesses of the median?
- it is less sensitive than the mean
what is the mode?
- most frequently occurring score/value
- two modes = bi-modal
what are strengths of the mode?
- easy to calculate
what are weakness of the mode?
- not a very useful piece of information
what are the measures of dipersion?
- range
- standard deviation
what is the range?
highest value - lowest value +1
why do you add 1 when calculating the range?
mathematical correction, raw score may have been rounded up or down
what are the strengths of ranges?
- easy to calculate
what are the weaknesses of the range?
- only takes into extreme values
- unrepresentative of the data set as a whole
what is standard deviation?
- a single value that tells us how far scores deviate from the mean
what does a large standard deviation show?
greater dispersion or spread within the data
- not all ppts were affected by the IV in the same way
what does a low standard deviation show?
data is tightly clustered around the mean
- implies that all ppts responded in a fairly similar way
what are strengths of standard deviation?
more precise measure of dispersion than the range
what are the weaknesses of standard deviation?
it can be distorted by a single extreme value
