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Abstract
In a two-stage stratified procedure for sampling herbage yield, plots are stratified by a pin frame in stage one, and clipped. In stage two, clippings from selected plots are sorted, dried, and weighed. Sample size and distribution of plots between the two stages are determined by equations. A way to compute the effect of number of pins on the variance of estimated herbage yield has been developed. It was tested by using a sampling budget and a simulated population of
Bromus mollis (soft chess), and worked reasonably well with other annual plant populations. But application to other plant communities should be made with prudence.
Citation
O''Regan, William G.; Conrad, C. Eugene. 1975. Number of pins in two-stage stratified sampling for estimating herbage yield. Res. Note PSW-RN-300. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 4 p
