TWO VARIABLE ANALYSIS
By: Leslie Hamilton, Joseph Miller, Leah Brown, Racquel Thwaites, Ashlee Touzalin
Two variable analysis Definition: this involves the analysis of the
relationship between two variables
As one variable goes up, the other changes in a predictable way (either mostly goes up or mostly goes down)
Uses of two variable analysis
Science
Medicine
Educational research
Business
Geotechnology engineering - branch of civil engineering that focuses on earth, rock and subterranean water and their relation to planning, execution and operation of engineering projects.
INDEPENDENT AND DEPENDENT VARIABLE
Independent variable is a variable that stands alone and isn't changed by the other variables you are trying to measure.
Dependent variable is the variable that depends on other (independent variable) factors.
The value of the dependent variable depends on the value of the independent variable
Example The number days of your last hair cut and the
length of your hair
Independent:
Dependent:Days
Length
What is a Scatter Diagram
A scatter diagram is a tool for analyzing relationships between two variables.
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Time/ temperature scatter graph
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Identifying when and how to use
One variable is plotted on the horizontal axis and the other is plotted on the vertical axis
The pattern of their intersecting points can graphically show relationship patterns
Used to prove or disprove cause-and-effect relationships.
by itself it doesn’t prove that one variable causes the other
diagram can show that two variables are from a common cause that is unknown
When to use it To examine theories about cause-and-effect
relationships
to search for root causes of an identified problem
to design a control system
How to create a scattered diagram
Collect data
Draw the diagram
Label both axes
Plot the paired data
Title and label the diagram.�
Correlations Correlation is a measure of the strength of the
relationship or association between two variables
Positive Correlation For a generally upward shape in the points
plotted we say that the correlation is positive.
Independent variable the dependent variable
Negative Correlation For generally downward shape we say that the
correlation is negative.
independent variable the dependent variable
No Correlation For randomly scattered points with no upward or
downward tend, we say there is no correlation.
Types of relationshipsPositive : When the variable tend to have a
generally upwards shape
Negative: When the variable tend to have a generally downwards shape
Linear: When the variables seem to flow into a form of a line hence the word linear
Correlation strengths Strong: Which is when most of the variable are
closely together along the best line fit
Moderate: When the variables along the best fit, are slightly dispersed
Weak: when the variable is spread out unevenly, and most of the variables are not close to the best line fit.
Example Let's decide if studying longer will affect Regents
grades based upon a specific set of data. Given the data below, a scatter plot has been prepared to represent the data.
What is line of best fits A line of best fit is a line you draw through a
scatter graph to find the direction of an association between two variables.
How is it drawn “by eye”?Just an estimate
Therefore may look slightly different from others since not everyone sees the same way
How to find the equation of the line of best fits using coordinate geometry
Using the equation y = mx +c (there is no c in this example)
Use a point that is on the line of best fit for x and y
Or you could just find the gradient of the line
What we use the line of best fit to do?
The line of best fit is used to judge the two sets of data and determine their correlation.
To calculate values of one variable when given the other
What is interpolation and extrapolation?
Interpolating is using the values inside the poles
extrapolating is using the values outside the poles
these poles are created by using the lowest and highest value of x on the scatter diagram
it is unreliable to extrapolate outside the poles but reasonable to interpolate between them
Answer
Moderate, positive and linear
Answer
a) X= 6.88 Y= 83.5c) Moderate and positive f) About 95 thefts per day
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time/ temperature scatter graph
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Ashlee -Two variable Analysis and its uses / some of lines of best fits and correlations
Joseph - Independent and dependant
Leslie – Scatter graphs and correlations
Leah Lines of best fit
Racquel- Interpolation and extrapolation ( the two questions)
The End Hope you learned something