# How do you describe the association?

No association: Hard to find a pattern showing a relationship between the variables. STEP 1: Make a scatterplot; describe the form, direction and strength of the relationship. Before doing the scatterplot you need to decide which variable is the explanatory variable and which is the response variable.
A.

### What does a scatter plot tell you?

Scatter plots are similar to line graphs in that they use horizontal and vertical axes to plot data points. However, they have a very specific purpose. Scatter plots show how much one variable is affected by another. The relationship between two variables is called their correlation .
• #### What is the line of best fit on a scatter plot?

A line of best fit is a straight line drawn through the center of a group of data points plotted on a scatter plot. The line of best fit shows whether these two variables appear to be correlated and can be used to help identify trends occurring within the dataset.
• #### What does a scatter plot tell you?

Scatter plots are similar to line graphs in that they use horizontal and vertical axes to plot data points. However, they have a very specific purpose. Scatter plots show how much one variable is affected by another. The relationship between two variables is called their correlation .
• #### Why would you use a box plot?

It is often used in explanatory data analysis. This type of graph is used to show the shape of the distribution, its central value, and its variability. In a box and whisker plot: the ends of the box are the upper and lower quartiles, so the box spans the interquartile range.
B.

### What is a positive association?

Positive correlation is a relationship between two variables in which both variables move in tandem. A positive correlation exists when one variable decreases as the other variable decreases, or one variable increases while the other increases.
• #### What is positive and negative association?

Recall, Positive/Negative Association: • Two variables have a positive association when the values of one variable tend to increase as the values of the other variable increase. • Two variables have a negative association when the values of one variable tend to decrease as the values of the other variable increase.
• #### What does linear association mean?

A relationship of direct proportionality that, when plotted on a graph, traces a straight line. In linear relationships, any given change in an independent variable will always produce a corresponding change in the dependent variable.
• #### Which is the strongest correlation?

The greater the absolute value of the Pearson product-moment correlation coefficient, the stronger the linear relationship. The strongest linear relationship is indicated by a correlation coefficient of -1 or 1. The weakest linear relationship is indicated by a correlation coefficient equal to 0.

Updated: 2nd October 2019