correlations and line of fit students will explore the line of fit/correlations of data sets without...
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Correlations and Line of Fit
Students will explore the line of fit/correlations of data sets without having to create a scatterplot.
Explanatory/Response Variables For the following variables, please decide if they are random
variables or explanatory/response, and if they are explanatory/response…decide which one is which.
A family’s income and the years of education their eldest child completes.
Your pay and the type of job you have.
Your IQ test score and your school GPA
The age you start crawling and when you stopped eating baby food.
Correlation What is a brief definition of correlation?
Draw a scatterplot that would have a correlation of exactly 1.
Draw a scatterplot that would have a correlation of exactly -1.
Draw a scatterplot that has a correlation of 0.
Draw a scatterplot that has a correlation of -0.7 and another at 0.5
Line of fit Instead of calling the line of fit, the line of fit, we are going to
call the regression line.
The regression line helps us predict what will happen in the future.
We can use our calculator to find it.
Y = a + bx where b is the slope and a is the y-intercept.
Practice finding the regression line
Age x in months
Height y in centimeters
18 76
19 77
20 78
21 78
22 79
23 80
24 80
25 81
26 81
27 82
28 83
29 84
Use your calculator to find the regression line.
Predict the height of someone at 32 months.
Predict the height of someone at 240 months.
If someone is 90 centimeters, how old are they?
What does it mean? Explain what the slope and y-intercept means to each
problem in the real world.
SAT math score = 572 – 1.04 x percent taking the test
Pay at your job = 100 + 1.75 x years on the job
Weight of soap = 54 – 2.38 x days