Chapter 4 Flashcards
Which diagram is used to represent bivariate data?
A scatter diagram.
What goes on the x-axis of a scatter diagram?
The independent/explanatory variable. (Can control this variable).
What goes on the y-axis of a scatter diagram?
The dependent/response variable. (Can measure this variable).
What does correlation describe?
The nature of the linear relationship between 2 variables.
What are the 5 descriptions of linear correlation?
Strong positive correlation
Weak positive correlation
Strong negative correlation
Weak negative correlation
No (linear) correlation
What is a causal relationship between 2 variables?
When change in one variable causes a change in the other.
When 2 variables show correlation, what must you take into account?
That correlation doesn’t equal causation. You must use common sense to determine this. (SHIT)
What is the equation of a regression line?
y = a + bx
What does b tell you in a regression line?
b is the change in y for each unit change in x.
If the data is positively correlated, b will be positive.
If the data is negatively correlated, b will be negative.
What does a tell you in a regression line?
a is the y intercept. so what x is when y=0.
What should you only use the regression line for?
To make predictions for values of the dependent variable that are within the range of the given data.
What is extrapolation?
extrapolation - making a prediction based on a value outside the range of the given data.
