scatterplot2.JGR {CADStat} | R Documentation |

## Draws a scatterplot of bivariate data

### Description

Creates a scatterplot - a plot displaying the relationship between two
variables. A linear regression line or loess smooth can be overlayed.

### Details

A scatterplot provides a graphical means of determining the relationship
between two variables. Important relationships that can be observed are
linear, higher-order polynomial, exponential, or logarithmic. Along with
the general pattern, it is possible to qualitatively determine the strength
of the relationship. The "closer" or "tighter" the points are to the
general shape, the stronger the relationship. A scatterplot is also a
useful tool for identifying potential univariate or bivariate outliers
(observations that are much larger or smaller than the other data points).

After gaining insight into the general relationship of the variables, a
quantitative analysis method may be more easily chosen:

Correlation analysis, which helps determine the strength of the
linear relationship between two variables.

Linear regression, which fits a linear model to two or more
variables.

Quantile regression, which fits a model to conditional quantiles
of the dependent variable rather than to the conditional mean.

**User Interface**

To create a scatterplot, select "Scatterplot" from the "Analysis Tools"
menu. A dialog box will appear that allows the user to enter plotting
parameters. Select the data set of interest from the pull-down
menu, or browse for a tab-delimited text file. The Data
Subsetting tab can be used to select a subset of the data file
by choosing a variable from the pull down menu and then
selecting the levels of that variable to include. You can hold
down the <CTRL> key to select multiple levels. A separate plot
will be produced for each unique setting of the subsetting
variables. Select a variable to plot on the x-axis and a
different variable to plot on the y-axis. A regression fit can
be overlaid on the scatterplot. If Linear Regression Line is
selected, a straight line fit is drawn. If Loess Smooth is
selected, a nonparametric loess fit is drawn. You may change the
axes labels and plot title by typing them in the Labels dialog.
The output is simply the scatterplot graph with any overlaid fits
requested.

### See Also

To learn about boxplots, see boxplot.

To learn about correlation analysis, see cor.

To learn about linear regression, see lm.

To view the help file for the general R plotting function, see
`plot`

.

[Package

*CADStat* version 3.0.8

Index]