AP stats unit 1A one-variable data

if p-value <= 0.05

statistically significant

retrospective study

examines existing data

prospective study

follows individuals over time

population

(N) the entire group of individuals

sample

(n) info from a subset of population

types of variables

categorical/quantitative

categorical variables

nominal (unordered), ordinal (ordered), binary (2 categories)

quantitative variables

discrete (countable #), continuous (continuum #)

a valid statistical investigative question has what key parts?

proportion and populationp

parameters

values from the population

statistics

values from the sample

observational unit

a single member within the sample

frequency

exact count of a value

relative frequency

count expressed in fractions of the total

does categorical data have shape?

no

area principle

area occupied by a part of the graph should correspond to the magnitude of the value

types of graph to represent categorical data

bar graph, pie chart, mosaic plots

types of graphs to represent quantitative data

stem plots, histogram, dotplots

describing distribution

Context Shape Outliers Center Spread (CSOCS)

what causes graphs to be misleading

pictographs, vertical axis not starting at 0

types of shapes

symmetric, skewed left, skewed right, uniform

mean is roughly equal to the median

symmetricme

mean is equal to median

uniformme

mean is greater than the median

skewed right

mean is less than the median

skewed left

standard deviation

the average distance of values from the mean

is mean greatly affected by outliers?

yes

outliers

values that lie extremely far from other values

how to find outliers

above/below TWO standard deviations

1.5 x IQR of the Q1 and Q3 values

can you see clusters in a boxplot?

no

standardized/z-score

how many standard deviations away from the mean a data value falls

precentile

describes the location of a data value in a distribution