AP Stat Unit 1 Vocab

Basic terms

individuals

objects described by a set of data, could be people, animals, or things

variable

characteristic of an individual, can take different values for different individuals

categorical variable

places individuals into one of several groups or categories

quantitative variable

takes numerical values for what makes sense to find an average

distribution

tells what values a variable takes and how often it takes these values

inference

conclusion drawn that goes beyond the data at hand

frequency table

shows the frequency of data in each category

relative frequency table

shows the percent of data in each category

pie chart

shows distributions of data in a circle, emphasizes category’s relation to the whole

bar graph

shows categories of data in bars, compares quantities measured in the same units

dotplot

data values are shown by dots above their location on a number line

shape

major peaks, clusters or gaps of values, potential outliers, symmetry, skewness

center

mean or median that roughly splits data in two

spread

tells variability in data, could be range, or smallest and higher values

outliers

values that differ from the overall data pattern

symmetric

right and left sides of graph are approximately mirrors of each other

skewed to the right

right side of graph is notably longer than left side, positively skewed

skewed to the left

left side of graph is notably longer than the right side, negatively skewed

unimodal

one peak in the graph

bimodal

two peaks in the graph

stemplot

(stem and leaf plot) separates first digit(s) as a stem, and the last digits as leaves, goes least to greatest

histogram

shows the frequency of the data found between ranges

mean

average of all the data

median

highest value or average between middle values, resistant to skewing

range

highest value minus lowest value

quartiles

1st Q contains 25% of data, 3rd Q contains 25% of data, 2nd Q is the median

interquartile range (IQR)

3rd Q value minus 1st Q value

five-number summary

summary of data showing minimum, Q1, median, Q3, and maximum

boxplot

has dots at min. and max. values, boxes to show Q1 and Q3 distribution

standard deviation

distance between a value and the mean, square root of variance

variance

average of squared distances from the mean

resistant

a measure that won’t be altered by outliers or extremes

1.5 x IQR rule

subtract this from Q1 to find lower outliers, add to Q3 to fined higher outliers, anything outside added/subtracted values is an outlier

what is used with symmetrical data that has no outliers

mean and standard deviation

what is used with asymmetrical data that has outliers

median and IQR

quantitative graphs

histograms, dotplots, stemplots, boxplots, frequency charts

qualitative graphs

pie charts, bar graphs