A systematic random sampling (SRS) procedure provides an unbiased and efficient sampling technique. It is preferable to other forms of sampling when multiple sampling runs are implemented, either for a given region of interest, or for several regions of interest when multiple tissue groups are examined.
If a region of interest is sampled more than once (or if a series of similar regions of interest are sampled), the sample area/volume at each sample site and the distance between the sample sites do not vary. But the placement of the systematic sampling scheme for each sample run is randomized.
This consists in defining a random selection process to select a small number of uniformly spaced sections from a complete sequence of sections.
You need to determine the exact number of sections to sample and the section increment based on considerations about estimation precision (Determining Sampling Precision).
Example: The number of sections to sample is 30 and the section interval is 4. The first section sampled is a random selection of 1, 2, 3 or 4.
When you sample several series of sections, randomly select a new starting section for each series, but use the same section increment for all the series.
To set up a systematically random sample of serial sections
If you plan on using a workflow, these steps are unnecessary.