Please Turn to Yesterday's Handout

Time for Sugar to Dissolve Experiment Independent Variable Dependent Variable Control Variable(s) As you run to the store, how does your distance change with time? Time Distance How does temperature affect how quickly a sugar cube will dissolve? Temperature Time for Sugar to Dissolve Is there a relationship between human foot length and height? Foot Length (could go either way) Height What is the relationship between the world’s population and time? Population Is there a relationship between the maximum weight a person can bicep curl versus the maximum that a person can bench press? Weight Person Can Bench Press Weight Person Can Bicep Curl Is there a relationship between the number of words on a page versus the area of a book cover? Area of Book Cover Number of Words on a Page

Dependent Variable (placed on vertical axis: y) A dependent variable is a variable dependent on the value of another variable Independent Variable (placed on horizontal axis: x) The independent variable causes an apparent change in, or affects the dependent variable

Examples: In a call centre, the number of customers serviced depends on the number of agents At ski resort, the amount of sales, in $, depends on the amount of snow The amount of bacteria on your hands depends on how often frequently you use hand sanitizer. dependent variable (y) independent variable (x)

A scatter plot shows a ____________ correlation when the pattern rises up to the right. This means that the two quantities increase together. A scatter plot shows a ____________ correlation when the pattern falls down to the right. This means that as one quantity increases the other decreases. A scatter plot shows _____ correlation when no pattern appears. Hint: If the points are roughly enclosed by a circle, then there is no correlation. positive negative no

Strong or Weak Correlation? If the points nearly form a line, then the correlation is ___________________. If the points are dispersed more widely, but still form a rough line, then the correlation is _______________________. strong weak Hint: To visualize this, enclose the plotted points in an oval. If the oval is thin, then the correlation is strong. If the oval is fat, then the correlation is weak.

Does age have a strong positive correlation with height? Explain. Do you think the variables are placed appropriately on the axes? c) Would weight vs. age show a strong positive correlation? d) Can you think of a variable that does have a strong positive correlation with age? e) Can you think of a variable that has a strong negative correlation with age?

Line of Best Fit …affectionately known as LOBF

All about the LOBF… What is it? How do I draw it? shows a trend or pattern on a scatterplot used to make predictions How do I draw it? models the trend/pattern models the trend/pattern through as many points as possible equal points above and below the line

Line of Best Fit trend pass equal To be able to make predictions, we need to model the data with a line or a curve of best fit. Guide for drawing a line of best fit: 1. The line must follow the ______________. 2. The line should __________ through as many points as possible. 3. There should be ____________________________ of points above and below the line. 4. The line should pass through points all along the line, not just at the ends. trend pass equal

Which one of these is the best LOBF? And what is wrong with the others? Line not in middle of points #1 #2 Doesn’t model trend #3 #4 Wrong for all kinds of reasons!

Return to front side of hand out and make lines of best fit on each of the given 6 graphs.

You can use LOBF’s to make predictions for values that are not actually recorded or plotted. Interpolation Extrapolation prediction involving a point within the set of data prediction involving a point outside the set of data (line needs to be extended)

Fill in blanks on handout

Using our height and humerus data… How tall would a person be that had a humerus of 44 cm? 181 cm tall Extend the line! Is this interpolation or extrapolation? exptrapolation

Using our height and humerus data… How long would a person’s humerus be that was 163 cm tall? 28 cm long Is this interpolation or extrapolation? interpolation

Makin’ sure you get it! See bottom of handout