Looking for global trends

To identify a global trend in your data, look for a curve that is not flat on the projected plane.

If you have a global trend in your data, you may want to create a surface using one of the deterministic interpolation methods (for example, global or local polynomial), or you may wish to remove the trend when using kriging.

Steps:

1. Click the point or polygon feature layer in the ArcMap table of contents that you want to explore.
2. Click the Geostatistical Analyst drop-down menu on the Geostatistical Analyst toolbar, click Explore Data, then click Trend Analysis.
3. On the Trend Analysis interface, click the Trend and Projections choice under the Graph Options.
4. Explore the bold lines on the vertical walls of the graph. These lines are indicating trends. One trend line goes along the x-axis (typically showing the longitudinal trend), while the other one shows the trend along the y-axis (typically the latitudinal trend). It is very useful to change the Order of Polynomial while examining the trends.

Tip:

It can be very helpful to check for trends in directions that vary from the standard N–S and E–W. To enable such a view, rotate the trend axes by scrolling the upper wheel on the right-hand side of the tool, just under the main display window.