Everything about AP Stats chapter 1 through 5

Individual cases

The rows of a data table correspond to individual cases about Whom

Respondents

Individuals who answer a survey

Subjects or participants

People on whom we experiment

Experimental units

Animals, plants, websites, inanimate subjects

Records (in a database)

Rows

Generic word for Records

Cases (any event the rows represent the who of the data)

Variables

The characteristics recorded about each individual

Often, the cases are a _________ of cases selected from some larger population that we’d like to understand.

sample

Example of identifier variables

Social Security, student ID numbers, or Amazon Standard Identification Number (ASIN)

Categorical Variables

What a group or category each individual belongs to.

Quantitative variable

When a variable contains measured numerical values

Quantitative variables typically have _____

units

Area Principle

Says that the area occupied by a part of a graph should be proportional to the magnitude of the value it represents

Categorical variables are easy to summarize in a ________________ that lists the categories and how many cases belong to each one.

Frequency Table

Relative Frequency Table

Displays percentages (or proportions) rather than the counts in each category

Distribution

They show how the cases are distributed among the categories

Pie Charts

Show the whole group of cases as a circle. They slice the circle into pieces whose sizes are proportional to the fraction of the whole in each category

Categorical Data Condition

The data are counts or percentages of individuals in non-overlapping categories

When presented like this, in the mar-gins of a contingency table, the frequency distribution of one of the variables is called its _______________

Marginal distribution

conditional distribution

shows the distribution on one variable for a subgroup of individuals that satisfy a condition on the other variable

segmented bar chart

Bars stacked on of each other

Independent Variables

In a contingency table, when the distribution of one variable is the same for all categories of another variable

Side-by-side bar chart

A graph that weaves together two or more conditional distributions

Simpson’s paradox

to be careful when you average across different levels of a second variable. It’s always better to compare percentages or other averages within each level of the other variable. The overall average may be misleading

Gaps in a histogram

Actual gaps in the data and indicating an interval where there are no values.

Relative frequency histogram

replacing the counts on the vertical axis with the percentage of the total number of cases falling in each bin.

What is a Dotplot

A simple display. It just places a dot along an axis for each case in the data.

Cumulative distribution plot or known as a ogive

Quantitative Data Condition

The data are values of a quantitative variable whose units are known

When you describe a distribution, you should always tell about three things

Shape, spread, and center

Does the histogram have a single, central hump of data or several separated humps?

Modes

Unimodal

A histogram with one peak

Bimodal

Histograms with two peaks

Uniform

A histogram that doesn’t appear to have any obvious mode and in which all the bars are approximately the same height

To tell the histogram symmetric

Try to fold it along a vertical line through the middle and have the edges match pretty closely, or are more of the values on one side

Tails within a distribution

Thinner ends of a distribution

Skewed in a distribution

If one tail stretches out farther than the other, the histogram is said to be skewed to the side of the longer tail

Outliers in a distribution

Stand of away from the body of the distribution

Median

The middle value that divides a histogram into two equal areas

Range

The difference between the maximum and minimum value

Range Formula

Range = max - min

5-number summary

distribution reports its median, quartiles, and extremes (maximum and minimum)

Upper fence

= Q3+1.5 times IQR

Lower fence

= Q1 - 1.5 times IQR

What does Σ mean (Greek letter captial letter sigma)

Sum

(sigma is “_” in Greek)

S

Sample Mean Formula

x̄ = ( Σ xi ) ÷ n

x̄ means in the sample mean formula

Denotes the average value of the samples or sample mean

What does Σ mean

Standard Deviation

xi means in the sample mean formula

xi refers all X sample values

n means in the sample mean formula

stands for the number of sample terms in the data set

What is the sample mean formula?