Scatter Plots and Associations

​Scatter Plots and Association

NC Standards

NC.8.SP.1: Construct and interpret scatter plots for bivariate measurement data to: 

• investigate patterns of association between two quantities. 

• investigate and describe patterns such as clustering, outliers, positive or negative association, linear association, and nonlinear association.

NC.8.SP.2: Model the relationship between bivariate quantitative data to:

• Informally fit a straight line for a scatter plot that suggests a linear association.

• Informally assess the model fit by judging the closeness of the data points to the line.

NC.8.SP.3: Use the equation of a linear model to solve problems in the context of bivariate quantitative data, interpreting the slope and -intercept.

Essential Questions

• How can you construct and interpret a scatter plot?

• How can you describe the data set on a plot?

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• Scatter plots are graphs that use points to display numerical data with two variables, or bi-variate data.

• Scatter plots can help determine if one variable has an effect on the other, or if there are overall trends, patterns or relationships between the variables.

Fill in the Blank

Zara surveyed shoppers at a mall to see how many items they’d purchased and the total amount of money they’d spent at the mall. She used the data to create the scatter plot shown.

How many shoppers did Zara survey?

Fill in the Blank

Zara surveyed shoppers at a mall to see how many items they’d purchased and the total amount of money they’d spent at the mall. She used the data to create the scatter plot shown.

Does the number of items purchased seem to have an effect on the amount of money a shopper spent?

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​As one variable increases, the over variable increases. (The variables change in the same direction.

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​The change in one variable has no effect on the second variable.

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​As one variable increases, the over variable decreases. (The variables change in opposite directions.

​The number of shows a person owns and the number of states they've visited

​The size in ounces of a steak and the cost of the steak

​The number of days since watering a plant and the moisture level of the soil

Match

Match the type of association you'd expect to see between the following variables

• The number of shoes a person owns and the number of states they've visited

• The size in ounces of a steak and the cost of the steak

• The number of days since watering a plant an the moisture level of the soil

no association

positive

negative

• no association

• positive

• negative

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​If the data points are close together, the association is strong, and if the data points are widely spread, the association is weak.

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​If a straight line can be drawn to show the overall trend of a scatter plot, the association can be described as linear.

Multiple Select

Which graph(s) show linear association

Multiple Select

Which graph(s) show non-linear association

Multiple Choice

Which scatterplot shows the strongest association?

Multiple Choice

Which scatterplot shows the weakest association?

Draw

Draw a line from each scatterplot to the best description of its association and then to the variables is would most likely represent. Not all choices will be used.

Essential Questions

• How can you construct and interpret a scatter plot?

• How can you describe the data set on a plot?