Pollen analysts often add Lycopodium tablets (obtained from Lund University, Sweden) to pollen preparations during processing, in order to calculate microfossil concentrations (see Stockmarr 1971). Each batch of tablets comes with an estimate of the spore content, given usually as the mean and standard deviation of five tablets. Depending on the characteristics of the sample, it is not always necessary to use five Lycopodium tablets. So palynologists may need to calculate statistics for other numbers of tablets. Taking Batch 710961 as an example and assuming that Lund is correct in their statistics that five of their Lycopodium tables in this batch contain (mean ± standard deviation) 69,556 ± 1541 spores, then what are the statistics for one, two, or three tablets?

The mean number of grains in a group of N tablets = N times the mean number of grains per tablet (Y). Lund determined that their five-tablet mean was 69,556, so a single tablet's mean is 13,911, as they indicate.

The standard deviation of a group of N tablets = square root of N times the standard deviation of the individual tablet; that is SQR(N) x s. (See Maher 1981, pp. 158-159). So the standard deviation for a single tablet is 689. Similar computations can be done for other numbers of tablets, as shown in the table below.

Number of Tablets	Group Mean	Group S.D.	Coefficient of Variation
1	13,911	689	4.95%
2	27,822	975	3.50%
3	41,733	1193	2.90%
4	55,644	1378	2.50%
5	69,556	1541	2.20%
10	139,110	2179	1.60%

References

Maher, L. J., 1981. Statistics for Microfossil Concentration Measurements Employing Samples Spiked with Marker Grains. Review of Palaeobotany and Palynology 32:153-191.

Stockmarr, J., 1971. Tablets with Spores used in Absolute Pollen Analysis. Pollen et Spores 13:615-621.

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[Editor's note: This item was elicited in response to a recent question by Martin Head posted on the POLPAL discussion list. It is reproduced here, in slightly modified form, with permission from Dr Maher.]

For more information on Lycopodium spore tablets, including details about where to order them from, please take a look at Equipment and Laboratory Supplies.]  

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This article first appeared in CAP Newsletter 20(2):26, 1997.