AP stats Unit 1 Chapter 1

Individual

Object described in a set of data ( animals, people, or things)

Variable

Can take different values for different individuals

Categorical variable

Places individuals into a particular group / category

Quantitative variable

Takes number values

Discrete variable

Qv that takes a fixed set of values with gaps

Continuous variable

Qv that can take any value in an interval on the number line

Distribution

Tells us what values the variable takes and how often

Frequency table

Shows # of individuals having each value

Relative frequency table

Shows the proportion/ percent of individuals having each value

Bar graphs

Shows each category as a bar

Pie chart

Shows each category as a slice of a pie

Two -way table

Summarizes data on the relationship b/w 2 categorical variables

Association

Knowing the value of one variable helps predict the value of the other

Dot plot

Shows each data as a dot

Symmetric distribution

Right side of the graph is approximately a mirror of the left side

Skewed to right

Right side of the graph is much longer than the left

Skewed to left

Left side of the graph is much longer than the right side

Describing distribution

C- center

U-unusual features (outliers)

S- shape

S-spread

Mean

Average of the distribution

Medicin

Midpoint of the distribution

Static

Number that describes a sample

Parameter

Number that describes a population

Range

Measure of variability for a distribution

Standard deviation

Describes the distributions variability

Variate

Average of the squared deviations from the mean

IQR

Q3- Q1

Resistance

Median is resistant, mean is not. IQR is resistant, SD and range are not

IQR rule

If an observation is less than Q1-1.5*IQR or greater than Q3+1.5*IQR, it is an outlier

5 number summary

Minimum, Q1, median, Q3, maximum