Correlations (Situation)
Hours of exercise and weight loss.
Positive
What is an outlier?
A point that is distant (skewed) from the rest of the data.
Two points on the line of best fit are (4, 85) and (2, 70). Find the slope for the line of best fit using these points.
15/2
Why do we draw a line of best fit?
To predict a trend.
How do you make predictions using a scatter plot? (steps for the best fit)
1) Draw a line of best fit. 2) Determine the slope and y-intercept. 3) Write an equation and use it to make a prediction.
Temperature outside and amount of snow-cones sold
Positive
Describe what a positive correlation means for data.
As the independent variable increases the dependent variable will also increase.
The equation of the line for a graph comparing age and height (ft) is y=0.25x+1. How tall would someone that is 20 years old be?
6 feet tall
Line of best fit should connect all the dots (T/F). Justify
False. The best-fit line will most likely not go through all the points.
When most of the points are close to the line of best fit, but one is very far, this is called an _______________.
Outlier
Temperature outside and number of pets
No correlation
What does it mean for the data if there is no correlation?
The sets of data have no relationship to each other. You cannot draw a best-fit line.
What are the other names for the independent variable?
x, explanatory, or predictor
Do you use a line of best fit for no correlation? How / why?
No, if there is no correlation, it is not possible to predict the trend, therefore, it is not possible to have a best-fit line.
If I am graphing the number of shots made by a basketball player and the hours of practice he had, which would be the independent variable?
The number of hours played.
Time spent doing homework and number of missing assignments.
Negative
When the values of one data set increases and the other decreases, this is called a ___________ correlation.
Negative
What are the other names for the dependent variable?
y, response, predicted
When most of the points very closely follow the line of best fit, this is called a _______________ correlation.
Strong
On a graph showing the relationship between salary and years of experience which variable would be the dependent variable?
The salary.
Number of visitors to a water park and temperature.
Positive
How do you determine where to place the line of best fit?
There should be close to as many points as possible, and it should have an equal number of points above and below the line.
If there is no correlation-is the slope of the line positive or negative?
There's no line!
When the points on a scatter plot are scattered in the graph and do not follow a trend, this is called a ___________ correlation.
No correlation