Simple Unaligned grid is a 2d initial, systematic unaligned sample design. SADA uses a random starting point to generate a square grid system, but rather than sampling the center of each cell, a random location in the cell is chosen.
This design can help overcome the problem of missing features by randomizing within the cell. It increases the random element of the design while enforcing a regular distribution across the site. The lack of truly random design, however, may have an unknown impact on determining precision of simple statistical values or tests.
Availability
This sample design is available for all SADA files.
Steps
These are the steps that display in the Steps Window when this sample design is selected during the step Set sampling parameters. Click on the links below for more details about the following steps.
1. See the data, Draw/Edit Prior, Display empty plot
9. Add to results gallery (not available for empty SADA files)
Design-specific Parameters
When Simple Unaligned Grid is selected during the Set sampling parameters step, the Parameters Window changes to look like the following:
See Design Core samples or Show Ghost Image for an explanation of the core vs. single point sampling options.
If there are polygons, new samples will only be placed inside the active polygons.
Under Number of Samples, select the appropriate method. See Determining the Number of Samples for more information.
Under Random Seed, enter a number to generate the same random design. If the random seed is blank, SADA will generate a distinct random design each time.
Press Show the Results on the Steps Window and SADA will display the sample locations in the Graphics Window.
Note: Often this sample design will not return the exact number of desired samples due to constraints from the square grid type, the layering scheme, and the extents of the area.
To view the actual coordinates of the new sample points export the information to a comma delimited excel file by using the Output to File toolbar button in main form of SADA.