Measures Of Central Tendency And Dispersion

Question 1

Mean, median, mode

Answer 1

Mean = average calculated by adding up all the values in a data set af dividing by the number of values
-> more representative of the data as a whole
-> easily distorted by extreme values

Median = the central number in a data set when values are arranged from lowest to highest
-> extreme values don’t effect it
-> extremes may be important so missing is bad

Mode = the most frequently occurring value in a set of data
-> if there are multiple modes, its not helpful

Question 2

Measures of dispersion - range

Answer 2

Calculation of the spread of scores and is worked out by taking the smallest from the highest value and (usually) adding 1.
— adding one accounts for the margin of error in research

-> easy to calculate
-> only takes into account the extreme values; not representative of data set as a whole

Question 3

Standard deviation

Answer 3

A single value that tells us how far a score deviates from the mean

— the larger the STDV the greater the dispersion of data… not all the pts were effected by the IV
— the smaller the STDV the data is more tightly clustered… pts responded in similar way

-> more precise measurement than range; includes all the values from the data set
-> … so it can be distorted by a single extreme value