Chapter 4 - Correlation Flashcards
What is bivariate data?
Data which has pairs of values for two variables
How should you represent bivariate data?
On a scatter diagram
What is the control variable called?
The independent (or explanatory) variable
Where is the control variable plotted?
On the x-axis
What is the variable that the researcher will measure called?
The dependent (or response) variable
Where is the dependent variable plotted?
On the y-axis
What does correlation describe?
The nature of the linear relationship between two variables
What are the five types of correlation?
Strong negative Weak negative None Weak positive Strong positive
What is a causal relationship?
When a change in one variable causes a change in another
What must you do to see if two variables have a causal relationship?
Use the context of the question and common sense
What is the least squares regression line?
A line that minimises the sum of the squares of the distances of each data point from the line
How is the regression line written?
y=a+bx
What does the coefficient b tell you?
The change in y for each unit change in x
If b is positive, what does that show you?
The data is positively correlated
If b is negative, what does that show you?
The data is negatively correlated
