Unit 1 Flashcards
absolute frequency
number, directly from data
relative frequency
percentage
marginal relative frequency
margin/total
ex. % of all students who took PE
joint relative frequency
join of categories / total
ex. % of all students who chose math and chose art
conditional relative frequency
category / total limited by a condition
ex. % of the students who chose technology given they chose math
association
knowing the value of one variable helps predict the other
- will have different segmented bar graphs
quantitative variable
takes numerical value for measured/counted quality
categorical variable
values are category names / group labels
what can cause graphs to be misleading
- vertical axis not starting at 0
- using irregularly sized images for bar graphs
segmented bar graph
different categorical results shown as relative frequency out of a whole bar
- bars stacked up to make 100%
mosaic plot
Segmented bar graph where width of bars is proportional to group size
discrete data
type of quantitative data which has a countable number of values
continuous data
type of quantitative data that has an infinite number of possible values
when is a graph skewed left/right
higher values on right = skewed left
higher values on left = skewed right
describing distribution
SOCVaC
shape
outliers
center
variability
context
how to describe shape of a graph
unimodal or bimodal
right or left skewed or symmetric
how to describe center of graph
mean and median values
how to describe variability of graph
range, IQR, SD
How to interpret standard deviation
“The [context] typically varied by [SD] from the mean of [mean]”
Nonresistant statistics
Mean, standard deviation
Very impacted by outliers
Resistant statistics
Median
Not greatly impacted by outliers
Statistics to use for symmetric distribution
Mean, SD (nonresistant)
Statistics to use for skewed distributions or those with outliers
Median, IQR (resistant)
How to find outliers
IQR method:
Low outliers <Q1 - 1.5IQR
High outliers >Q3 + 1.5IQR
SD method:
Low < mean - 2SD
High > mean + 2SD
