Looking for scatter plot examples to better understand correlation?

See examples of scatter plots drawn using QI Macros.

To draw scatter plots using QI Macros:

Select your data.
Click on QI Macros menu > Box, Dot & Scatter > Scatter.
QI Macros will do the math and analysis for you.

Scatter plots are used to evaluate the correlation or cause-effect relationship (if any) between two variables.

There are three primary types of scatter plots:

Strong Positive Correlation

scatter plot example positive correlation

Data points are clustered along a trend line
Upward slope (as one variable increases so does the other).
R² is greater than .80

Strong Negative Correlation

scatter plot strong negative correlation

Data points are clustered along a trend line.
Downward slope (as one variable increases the other decreases.)
R² is greater than .80

No Correlation

Example of no correlation

Data points look like a shotgun blast
R² is less than .80

QI Macros makes me look like an expert

Calculating the Correlation of Determination

If R², the correlation of determination (square of the correlation coefficient), is greater than 0.8, then 80% of the variability in the data is accounted for by the equation. Most statistics books imply that this means that you have a strong correlation.

Can I create a Titration Curve in Excel using QI Macros?

Certainly! Make sure that you have a column of Volume data that represents your X-Axis, along with a column of pH data that represents your Y-Axis.

Select your data and then select the "Scatter" macro from the "Box, Dot & Scatter Plot" drop-down menu:

titration-chart-example

NOTE: Our Scatter Plot Diagram does NOT calculate the Equivalence Point for you - it can be identified by the end user where the graph is the steepest.

Also, if you have identified the Equivalence Point, simply hover over it - Excel will provide you with the value.

Scatter Plots can be made manually or in Excel. However, you have to find the right chart to get a trend line and Excel will not calculate the R² for you.

QI Macros Add-in for Excel can create a scatter plot in seconds and will calculate the slope and R² for you.