AP Stat ch 1 sect. 1.1 - 1.2 (Dot, Bar, & Pie) (excluding stem & beyond)

Bar graph

displays frequency (count)

Pie chart

displays relative frequency (percents)

Correlation

how close the data points are to each other

Unimodal

single-peaked (one mode)

Conditional distributions : describe how to calculate and add ALL conditional distributions to the "I'm Gonna Be Rich" table.

A 50-50 chance: Female = (696 / 1416) [# of woman 50-50 chance / total # of 50-50 chance for both genders]

Describe the conditional distributions presented in the graph in Figure 1.5 (pg 17):

Bar graph comparing the percents of females among those who hold each opinion about their chance of being rich by age 30

What is the purpose of using a segmented bar graph and side-by-side bar graph?

Can show conditional distribution ; Easy to compare

Shape of graph for dot plot or bar if *categorical* one way table

Cannot talk about shape because the bars can be in any order and therefore the shape can be changed

What type of data are pie charts and bar graphs used for?

Categorical data. They show the distribution more vividly.

One-way table

Categories | Quantities

Bar graphs represent each ________ as a bar and the bar heights give the category ________ or ________.

Category; Counts; Percents

Conditional Distributions

Describes the value of a particular variable specific to another variable

Two-way table

Describes two categorical variables

Marginal distribution

Distribution of values of categorical variable among all individuals described by the table

What makes a bad graph? What should you look for?

Don't replace bars with pictures. Look for bar graphs by their heights which represent the quantities.

"I'm Gonna Be Rich" on page 12, columns?

Gender

Bimodal

Has two peaks (2 modes)

Dot plot properties

Horizontal, scaled, labeled axis

Explain what it meant by an association between two variables;

If specific values of one variable tend to occur in common with specific values of the other. the relationship of two variables

Give an example of association. Use the "I'm Gonna Be Rich" example to describe association between gender and opinions.

Men more often rated their chances of being rich in the two highest categories; women said "some chance but probably not" much more frequently overall association is gender and opinion

A frequency table displays

Only the count

"I'm Gonna Be Rich" on page 12, what are the rows?

Opinion

Skewed to the left (negatively skewed)

The left side of the graph is much longer than the right side; i.e. the long tail is to the left or FEWER observations are on the left.

A relative frequency table displays

The percent Find the total & divide each count by the total to get the percent

Skewed to the right (positively skewed)

The right side of the graph is much longer than the left side; i.e. the long tail is to the right or FEWER observations are to the right.

Marginal distributions : describe how to calculate marginal distributions and add them to the table on prior page "I'm Gonna Be Rich" example.

There are 2367 females, 2459 males, & 4826 total in the data set. (2367 / 4826) 100% = 49% are female & 51% are male For opinion, there are 2367 females and 96 of them said they have 'almost no chance' (96 / 2367) = 4.05%

Describe how you decide which conditional distribution to compare (pg17, Think About It: explanatory vs. response).

Think about whether changes in one variable might help explain changes in the other. Explanatory is independent variable Response is dependent variable

What is the advantage of using dot plots?

This helps in describing the key features of a distribution of quantitative data ( Shape, center, spread, possible outliers)

Symmetric or roughly Symmetric (shape)

The left and right sides of the graph are approximately mirror images of each other.

Uniform

Same y value

Describe the conditional distributions presented in the graph in Figure 1.6 (pg 17):

Segmented bar graph showing the conditional distribution of gender for each opinion category.

When examining a distribution, you must *describe the overall pattern with these 4 components*

Shape Outliers Center Spread SOCS « *each step only applies to quantitative graphs*

*Describe the four steps to organizing a statistical problem:*

State - What's the question that you're trying to answer? Plan - How will you go about answering the question? Do - Make graphs and carry out needed calculations. Conclude - Give your practical conclusion in context of the problem.

When is the mean a good measure of the center?

When the quantitative graph is symmetric, otherwise median is good measure