Chapter 10
You collect data from 8 different countries, about what percent of people in each country speak at least two languages fluently. (bar, line, or pie)
Bar graph
What chart makes it easier for us to compare categories?
Bar graphs
What is seasonal adjustments?
When the expected seasonal variation is removed before the data is published
3 Things we look for when studying line graphs
1. Overall patterns/trends 2. Deviations from that pattern 3. Season Variation
What type of graph do we use to show how quantitative valuables change over time?
A line graph
Why is it generally a bad idea to use a pictogram?
-Can be misleading -Can be difficult for people to see the true difference between the categories
Advantages to bar graphs?
-Easier to draw -Natural way to order categories -Can visually compare different categories
3 disadvantages of using a pie chart
-Hard to draw by hand -No natural way to order them -Hard to compare the sizes of different categories
Why do we use data tables?
-To summarize large amounts of information -Show what is going on with data overall, instead of each individuals
3 principles for making good graphs
1. Has labels and legends 2. Making sure the data stands out 3. Paying attention to what people will see when they read the graph
Three things for a clear data table
1. Main heading (subjects and date of data) 2. Labels to identify variables and units they are measured in 3. Source of data
Bar charts and pie charts are most useful for what kind of variables?
Categorical variables
Example of a time when you need to use seasonal adjustment.
Graphing unemployment rates or prices of gasoline over time
What about pie charts makes them hard for people to visually read?
Hard to visually compare angles than lengths. One way to help make it easier to read is to add percentages for each category next to the wedges
What are pie charts used to show?
How a whole is divided into parts
Graphing the number of students at A&M each year from 1950 to 2016 (bar, line or pie)
Line graph
What is seasonal variation?
Pattern that repeats itself at known regular intervals of time
You do a survey of students at A&M and ask students whether or not they want the library to be open for longer hours. 50% say yes, 43% say no, and 7% are undecided. (bar, line, or pie)
Pie chart or bar graph
When making a data table, is it better to present as counts or as rates?
Rates; because they are more informative
What type of error do we commonly see in data tables?
Roundoff error
What is the distribution of a variable?
Tells us what values it takes and how often it takes those values
What do the wedges within the pie chart represent?
They represent each part; Size of the pie chart represents what portion of the whole fall into that category
What goes on the X (horizontal) and Y (vertical axes)?
Time on X and Variable you are measuring on Y
