How many check points does the SDTS recommend for accuracy testing?

The Spatial Data Transfer Standard (SDTS) recommends a minimum of 20 check points for accuracy testing. This recommendation is grounded in the need to ensure a robust assessment of positional accuracy across the dataset being evaluated. The selection of 20 check points helps to provide a statistically significant sample size that can yield more reliable and valid results.

By utilizing 20 check points, GIS professionals can sufficiently cover the extent of the dataset, allowing for a better representation of varying geospatial features and potential error sources. This approach also facilitates a thorough analysis of accuracy by enabling the comparison of the collected data against reference data at multiple locations, which is essential for generating trust in the spatial information being utilized. The choice of 20 strikes an optimal balance between practicality and the need for comprehensive testing.

The rationale behind the other options being lower than 20 check points would not meet this standard for thorough accuracy testing, potentially leading to skewed results or an incomplete understanding of the data’s accuracy.