Measures Of Central Tendency And Dispersion Flashcards
What are the 3 levels of measurements
Nominal, ordinal and interval
What is nominal data
Data which is in separate categories
What is ordinal
Data that is ordered in some way but difference between each is not the same
What is interval data
When the data is measured using units of equal intervals
What are the 3 measures of central tendency
Mean, median and mode
What is mean
The average where you add up all the numbers and divide by the amount of numbers
What is the median and how do you work it out
The middle number and you arrange the numbers in order and then work your way down to the middle
What do you do if there are 2 middle numbers for your median
Find their average by adding them up and divide by 2
What is the mode
Th most common data item
When do you use mean
When the data is interval data
When do you use median
When there is interval or ordinal data
When do you use mode
When there is nominal, ordinal or interval data
What is a strength of mean
It is the most sensitive measure of central tendency because it takes account of the exact distance between all of the values of all the data
What is a limitation of the mean
Due to sensitivity the value can be distorted by extreme values therefore becoming unrepresentative
What is the strength of median
Not affected by extreme scores, can be easier to calculate than the mean and can be used for ordinal data
What is the limitation of using the median
Not as sensitive, the exact values are not reflected, just the middle numbers
What is a strength of mode
Unaffected by extreme values and is the measure which can be used for nominal data.
What is a limitation of mode
It is not useful for explaining data when there is more than one mode (common choice)
What are the 2 types of measures of dispersion
Range and standard deviation
What does ‘measures of dispersion mean’
This refers to how dispersed or spread out data items are
What is the range
Highest value-lowest value
When would you use range
It can be useful for data which is both finding the same mean but has different ranges, it can further describe the data
What is a strength of using range
It is easy to calculate
what are the limitations of using range
.It’s affected by extreme values
.fails to take into account the distribution of values
What is standard deviation
It measures the spread of scores around the mean
What does a higher standard deviations suggest
That the scores/results are more spread out and that there is a larger variation in the results
What a re the strengths of standard deviation
.all values are used so it is more representative than the range
.its a more precise measure because it takes into account all the exact values
What is a limitation of standard deviation
It may hide some of the characteristics of the data set such as extreme values
