Chapter 9

Bell RingerGet out your notebook and prepare to take notes on Chapter 9

Convert your height to inches and be prepared to write this value on the whiteboard

Chapter 9Using Graphs to Analyze Data

9.1 Finding Mean, Median, and Mode (Page 412)9.2 Displaying Frequency (Page 418)

Essential Questions:

How do we find the mean, median, and mode of a set of values?

How do we choose which measure of central tendency to use?

When are line plots, frequency tables, and histograms useful?

9.1 Mean, Median, ModeCentral Tendency:Single value that summarizes how a set of data is centered

Mean:AverageSum of data values divided by the number of data values

Median:Middle value when the data values are arranged in numerical orderMean of two middle terms for an even number of data values

Mode:Item with the greatest frequencyPossible to have no mode, one mode, or more than one mode9.1 cont.Range:Measure of how spread out the data in a set areDifference between the greatest and least values in a set

Outliers:A data item that is much higher or lower than the other data itemsHave very little effect on the median and mode9.1 cont.

When to use mean, median, and mode:Example: The income of people who live in a town9.2 Displaying FrequencyFrequencyNumber of times a data item occurs

Line PlotDisplays data with X marks above each data value on a number line

9.2 cont.Frequency TableLists frequency of each item in a set of data

HistogramSpecial type of bar graph with no spaces between barsHeight of bar shows the frequencyIntervals are of equal size and do not overlap

9.1/9.2 - Closure

How do we find the mean, median, and mode of a set of values?Mean: the sum of data values divided by the number of data itemsMedian: the middle value or mean of the two middle valuesMode: the data value or values that occur most often

How do we choose which measure of central tendency to use?Mode: when data is not numericalMean: when there are no outliersMedian: when outliers are likely

When are line plots, frequency tables, and histograms useful?Quickly organize and display dataUseful when there are a large number of data values

9.1/9.2 - HomeworkPage 414-416, 2-24 evenPage 420-421, 2-22 even

Bell RingerGet out your 9.1/9.2 homework assignment

Get out your notebook and prepare to take notes on Section 9.4

Think of some ways that a graph could be misleading and list them in your notebook

9.4 Reading Graphs Critically (Page 428)

Essential Questions:

How do we recognize misleading graphs?

How do we choose the appropriate scale for a graph?

9.4 cont.Misleading Graphs:A scale that does not begin at zero may be misleading

Appropriate Graph Techniques:Scale must include least and greatest valuesScale must be divided into equal increments

9.4 cont.Example 1:

Explain why the new graph is more clear than the previous graph.9.4 cont.Note:

9.4 cont.Example 2:

9.4 cont.Example 3:The following graph makes it appear that almost twice as much is earned on Thursday as on Monday. Explain.

9.4 cont.Example 4:Using two different scales, make two bar graphs for the following data. Use a break symbol in only one of the graphs.

9.4 cont.Example 5:

The graph makes it appear that about 6 times as many people prefer apple juice to prune juice. Why?

The Vertical Scale has a break in it and it begins at 10.

How would you redraw the graph to more accurately portray the data?

9.4 - Closure

How do we recognize misleading graphs?Not starting at zero on the vertical scaleUsing intervals that are too small, too large, or unequal

How do we choose the appropriate scale for a graph?Use equal intervalsInclude entire rangeNo breaks in the actual data!9.4 - HomeworkPage 429-431, 1-7, 11-16

Bell RingerGet out your 9.4 homework assignment

Get out your notebook and prepare to take notes on Section 9.5

Order the following data values from least to greatest in your notebooks

9.5 Stem-and-Leaf Plots (Page 433)

Essential Question:

How do we read a stem-and-leaf plot?

9.5 cont.Stem-and-Leaf Plots:Graph that shows numerical data arranged in orderEach data item is broken down into a stem and a leafStem is on the left and the leaf is on the right

9.5 cont.Example 1:Make a stem-and-leaf plot for the following data:

9.5 cont.Example 2: Make a stem-and-leaf plot for the following data:

9.5 cont.Example 3: Make a stem-and-leaf plot for the following data:

9.5 cont.Back-to-Back Stem-and-Leaf Plots:Compare two data sets in one stem-and-leaf plot

9.5 cont.Example 4:Make a back-to-back stem-and-leaf plot for the following data:

9.5 - Closure

How do we read a stem-and-leaf plot?

Use the key to understand the relationship between stem and leaf9.5 - HomeworkPage 435-436, 1-9, 12

Bell RingerGet out your 9.5 homework assignment

Get out your notebook and prepare to take notes on Section 9.6

Recall the definition of median

9.6 Box-and-Whisker Plots (Page 438)

Essential Question:

How do we make a box-and-whisker plot?

9.6 cont.Box-and-Whisker Plot:Graph that summarizes a data set along a number line

Quartiles:Divide data into four equally-sized groups

Lower Quartile median of the lower half of the dataMiddle Quartile median of the entire data setUpper Quartile median of the upper half of the data

9.6 cont.Example 1:Write a statement that compares the data in the following box-and-whisker plots:

9.6 cont.Example 2:Write a statement that compares the data in the following box-and-whisker plots:

The range for the girls heights is greater than the boys.

Overall, the boys tend to be taller than the girls.

The girls upper quartile is equal to the boys lower quartile.9.6 cont.Example 3:Make a box-and-whisker plot for the following data:

9.6 cont.Example 3 (cont.):

9.6 cont.Example 3 (cont.):

9.6 cont.Example 4:Make a box-and-whisker plot for the following data:

9.6 - Closure

How do we make a box-and-whisker plot?

Order data

Find quartiles

Draw the box and the whiskers9.6 - HomeworkPage 440-441, 2-14 even, 17

Bell RingerGet out your 9.6 homework assignmentGet out your notebook and prepare to take notes on Section 9.7Plot the following points on the coordinate plane:

9.7 Making Predictions From Scatter Plots (Page 444)

Essential Question:

How can we make scatter plots and use them to find a trend?

9.7 cont.Scatter Plots:Graph that displays two sets of data as ordered pairsShows whether or not two sets of data are related

9.7 cont.Example 1:Make a scatter plot for the data in the table below:

Age (in years)Value (in thousands)9.7 cont.Example 2:Make a scatter plot for the data below:

9.7 cont.Trends:

9.7 cont.Trend Line:Drawn onto the scatter plotApproximates relationship between data setsUsed to make predictions about data values that dont appear on scatter plotPossible to have no trend line

Example 3:Use the following scatter plot to predict the height of a tree that has a circumference of 175 in:

88 ft9.7 - Closure

How can we make scatter plots and use them to find a trend?

Plot ordered pairsDraw a trend lineDecide whether trend is positive, negative, or no trendPredict values9.7 - HomeworkPage 446-447; 1-15

Bell RingerGet out your 9.7 homework assignment

Get out your notebook and prepare to take notes on Section 9.8

Pick your favorite type of pizza and put a tally mark in the appropriate box in the following table:PepperoniPlainMeat LoversTacoBuffalo Chicken9.8 Circle Graphs (Page 450)Essential Question:

How does a circle graph represent data?

9.8 cont.Circle Graph:Shows how parts of a data set relate to the wholeEntire circle = the wholeEach sector represents part of the wholeTotal must equal 100%

9.8 cont.Interactive Circle Graph

9.8 cont.Example 1:21.3 million people in the US use food pantries each year. How many people who use food pantries is 17 or younger?

How many people who use food pantries are 50 or older?9.8 cont.Example 2:Make a circle graph for the following data:

9.8 cont.Example 2:Make a circle graph for the following data:

9.8 - Closure

How does a circle graph represent data?

Represents a whole

Each sector is part of the whole9.8 - HomeworkPage 452-453; 2-9, 11-15

Bell RingerGet out your 9.8 homework assignment

Get out your notebook and prepare to take notes on Section 9.9

Which type of graph would you use to display the heights of every person in this building?

9.9 Choosing an Appropriate Graph (Page 456)Essential Question:

What factors go into our decision about what kind of graph is appropriate for a given set of data?

9.9 cont.Types of Graphs:

Line GraphShows change over time

Circle GraphShows parts of a whole, add to 100%

HistogramDivided into intervals, describes frequency

Box-and-Whisker PlotSummarizes large amounts of data

Stem-and-Leaf PlotData values are close together, exact values are important

Scatter PlotShows a relationship between two sets of data, ordered pairs

9.9 cont.Examples:Choose the appropriate graph to display the following sets of data:

Life span of different animals: bar graph or scatter plot??

Average household income and number of cars: histogram or scatter plot??

Price of a gallon of gas over 12 months: line graph or circle graph??

Students favorite type of music??

Daily high temperatures for the month of May??

Hours of television watched versus hours of working on homework??

9.9 cont.Example 2:Choose the appropriate graph for the following set of data:

Intervals AND Frequency

9.9 cont.Example 3:Choose the appropriate graph for the following set of data:

Circle Graph9.9 - Closure

What factors go into our decision about what kind of graph is appropriate for a given set of data?

Amount of data

Time relationships

Parts of a whole

Occur in intervals9.9 - HomeworkPage 457-459; 4-19 (DO NOT GRAPH)

Page 462-463; 1-14, SKIP 3, 8