Graphing Data
● Graph represents a quantity as a distance on a line
Axis - two lines that are perpendicular to each other
● Vertical line is y-axis
● Horizontal line is x-ais
● Each axis has a zero point
Origin - points where axis intersect (axis zero point)
● To make a two-variable graph we need 2 pieces of info: value of variable x and
value of variable y
Coordinates - two number lines that run perpendicular to one another
● X-coordinate is the length that’s the same value marked off on the x-axis
● Y-coordinate is the length that’s the same value marked off the y-axis
Scatter diagram - graph that plots value of one variable against the value of another
variable for a number of different values of each variable
● Reveals whether a relationship exists between two variables and describes their
relationship
Break
● Indicate that there are jumps from the origin, 0, to the first values recorded
● Able to bring the relationship into view
● Putting a break in one or both axes magnifies the relationship fills the graph
● Can be used to make a graph that lies and mislead
Correlation and Causation
● High correlation present - predict value of one variable from the value of other
variable
● But correlation doesn’t imply causation
● Sometimes a high correlation arises from a casual relationship
● High correlation can mean that two variables have a common cause
Graph Used in Economic Models
Economic Model - stripped-down, simplified description of any economy or of a
component an economy such as a business or a household
● Consists of statements about economic behaviour that can be expressed as
equations or as curves in a graph
● Patterns to look for in graphs are the four cases: variables move in same
direction, variables move in opposite directions, variables have a max or min,
variables are unrelated
Variables that Move in Same Direction
● Graph represents a quantity as a distance on a line
Axis - two lines that are perpendicular to each other
● Vertical line is y-axis
● Horizontal line is x-ais
● Each axis has a zero point
Origin - points where axis intersect (axis zero point)
● To make a two-variable graph we need 2 pieces of info: value of variable x and
value of variable y
Coordinates - two number lines that run perpendicular to one another
● X-coordinate is the length that’s the same value marked off on the x-axis
● Y-coordinate is the length that’s the same value marked off the y-axis
Scatter diagram - graph that plots value of one variable against the value of another
variable for a number of different values of each variable
● Reveals whether a relationship exists between two variables and describes their
relationship
Break
● Indicate that there are jumps from the origin, 0, to the first values recorded
● Able to bring the relationship into view
● Putting a break in one or both axes magnifies the relationship fills the graph
● Can be used to make a graph that lies and mislead
Correlation and Causation
● High correlation present - predict value of one variable from the value of other
variable
● But correlation doesn’t imply causation
● Sometimes a high correlation arises from a casual relationship
● High correlation can mean that two variables have a common cause
Graph Used in Economic Models
Economic Model - stripped-down, simplified description of any economy or of a
component an economy such as a business or a household
● Consists of statements about economic behaviour that can be expressed as
equations or as curves in a graph
● Patterns to look for in graphs are the four cases: variables move in same
direction, variables move in opposite directions, variables have a max or min,
variables are unrelated
Variables that Move in Same Direction
