Modeling distributions of data

percentile

value of P percent of the observations less and more than it

cumulative relative frequency

the sum of all relative frequencies up to and including a specific data point, representing the proportion or percentage of the dataset that is less than or equal to that value. It's calculated by first finding the relative frequency (frequency of an item divided by the total number of items) and then adding these relative frequencies in a running total

Q1 = 25th percentile

Q2 (median) = 50th percentile

Q3 = 75th percentile

percentile relation to quartiles

how many standard deviations a value is above or below the mean

z score

Observations bigger than the mean have positive Z scores

Observations smaller than the mean have negative Z scores

what does a z score tell you?

density curve

a graphical representation of a numerical distribution where the outcomes are continuous

facts about normal curves