relative frequency
the proprotion of the total N made up by a scores simple frequency
cumulative frequency
the sum of all the frequencies of all scores at or below a particular score
what are frequency distributions
graphs to display frequency info
what graph should you use to display frequency for interval and ratio data?
histogram and frequency polygon
what graph should you use for nominal and ordinal data?
bar graph
when are pie graphs used?
sometimes nominal data with only a few values
Do samples look like their parent population?
yes if the sample is large enough and multiple samples from the population will look alike