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Discovering Relationships in Data
Discovering Relationships in Data
A teacher wonders: "Do students who study more hours get better test scores?" To investigate, she collects data from 20 students about their study time and test results. But looking at two lists of numbers doesn't reveal patterns easily.
Enter scatter graphs! By plotting each student as a point (study hours on x-axis, test score on y-axis), she can instantly see if there's a relationship. Do the points trend upward? That suggests more study leads to better scores!
What is correlation?: Correlation describes the relationship between two variables. It shows how one variable changes when the other variable changes, but doesn't necessarily mean one causes the other.
Mathematics glossary
- What is correlation?
- Correlation describes the relationship between two variables. It shows how one variable changes when the other variable changes, but doesn't necessarily mean one causes the other.
- What is no correlation?
- No correlation (or zero correlation) occurs when there's no clear relationship between the variables. Points on the scatter graph appear randomly scattered with no obvious pattern.
Earn the mark scheme marks
Exam Tips for Scatter Graphs
- Choose appropriate scales - use most of the grid space
- Label axes clearly with variable names and units
- Plot points accurately - use a sharp pencil and read coordinates carefully
- Identify correlation type - strong/weak and positive/negative/none
- Line of best fit should be straight and balance points above/below
- Ignore outliers when drawing the line of best fit
- Extend the line appropriately for making predictions
- Be cautious with extrapolation - state that it's less reliable
Now try it yourself
Quiz · Question 1 of 14
A scatter graph shows that as temperature increases, ice cream sales also increase. This is an example of:
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