Scatter Plots!
What’s a Scatter Plot? Two sets of data are plotted as ordered pairs in the coordinate plane and show the relationship/correlation between two variables.
• The points in a scatter plot often show a pattern, or ______TREND___. • From the pattern or trend you can describe the ______CORRELATION . Variables The independent variable is located on the ______X axis. This variable does not depend on the other variable.
The dependent variable is located on the ______Y axis. This variable depends on the other variable.
Independent variable: ______Input (time)
Dependent variable: ______Output (Money)
Note: The independent variable comes first in the table of values. Correlation: the relationship between the dependent and independent variables
For our purposes and with our data… relationship, trend, and correlation are synonyms. Correlation/Relationship/Trend Positive Correlation: As x increases, y increases
Negative Correlation: As x increases, y decreases
No Correlation: The variables are not related so they are independent. Correlation/Relationship/Trend Linear Correlation: Looks like a line (there is a constant ratio), can be positive or negative
Non-linear Correlation: Data points have a curved pattern/trend
Strong Correlation: The data points are close to each other and have a clear pattern/trend.
Weak Correlation: The data points are farther apart but still have a pattern/trend. Examples: Describe the correlations in each scatter plot below: --Which variable is the independent variable? --Does Julie’s age depend on how tall she is? --Or does her height depend on how old she is? Example: Julie gathered information about her age and height from the markings on the wall in her house. Age (years) 1 2 3 4 5 6 7 8
Height (cm) 70 82 93 98 106 118 127 135
a) Label the vertical axis. b) Describe the trend in the data.
c) In a complete sentence, describe the relationship between Julie’s age and her height.