Exploring Data in Two Dimensions

Example

In this section you create a scatter plot of the wind_kts and min_pressure variables of the Hurricanes data set. The wind_kts variable is the wind speed in knots; the min_pressure variable is the minimum central pressure for each observation.

The min_pressure variable has a few missing values; those observations are not included in the scatter plot.


Open the Hurricanes data set.


Select Graph \blacktriangleright\,Scatter Plot from the main menu, as shown in Figure 6.6.



ugtwodscatmenu.png (3966 bytes)

Figure 6.6: Selecting a Scatter Plot

A dialog box appears as in Figure 6.7.


Select the variable wind_kts, and click Set Y.


Select the variable min_pressure, and click Set X.


Click OK.



ugtwodscatdlg.png (7948 bytes)

Figure 6.7: The Scatter Plot Dialog Box

A scatter plot appears (Figure 6.8) showing the bivariate data. The plot shows a strong negative correlation (\rho = -0.93) between wind speed and pressure. The plot also shows that most, although not all, wind speeds are rounded to the nearest 5 knots.

ugtwodscat.png (7680 bytes)

Figure 6.8: A Scatter Plot

You can click on any observation marker to select the observation. You can click while holding down the CTRL key to select multiple observations. You can drag out a selection rectangle to select a group of observations.

Previous Page | Next Page | Top of Page