Designing a pilot study
A pilot study is useful to determine the best parameters to use for each experiment (i.e., counting frame size, grid size, serial section interval, etc.).
It may be necessary to change the parameters for different groups within an experiment, especially if one group has a significant change in cell distribution. That is why we recommend a pilot study on one animal from each group within an experiment.
- Identify what you want to quantify.
- Inspect your tissue to identify important features and assess distribution and frequency of the object of interest.
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Prepare your tissue.
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Determine optimal mounted section thickness, guard zones, and disector height and sectioning orientation before sectioning.
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Determine the height sampling fraction (hsf).
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- Select a probe.
- Determine the number of sections to sample and the section sampling fraction (ssf).
- Section interval
- Systematic random sampling.
- Determine the number of sampling sites per section and the area sampling fraction (asf).
- Counting frame size.
- Grid size (see Preview SRS Layout)
- Determine the sampling precision.
- Target cell count
- Target CE (see Coefficients of Error)
- Use over-sampling (see Resample Oversample)
- Calculate the population estimate, based on the volume fraction (hsf x ssf x asf).
- Adjust parameters to refine estimate based on target cell count and target CE.
To decrease the number of cells sampled...- Increase the grid size to visit fewer sampling sites on each section.
- Increase the section interval (for example, counting every sixth section instead of every third section).
To increase the number of cells sampled...- Decrease the grid size to visit more sampling sites on each section.
- Decrease the section interval to sample more sections.