Background: Statistics is relevant to students and practitioners in medicine and health sciences and is increasingly taught as part of the medical curriculum. However, it is common for students to dislike and under-perform in statistics. We sought to address these issues by redesigning the way that statistics is taught.

The depth distribution of weed seed, their location in relation to soil aggregates, and the size distribution of soil aggregates were determined in fields that had been under continual conventional or reduced tillage for more than 12 years. Soil samples were taken at three depths in the spring and fall of 1982, and soil aggregates were classified into seven size classes by dry, rotary sieving. Subsamples were deflocculated and washed through sieves to recover weed seed. In the spring, 85% of all seed in the reduced-tillage and 28% of those in the conventional-tillage soil were in the 0- to 5-cm-depth layer. Conventional tillage incorporated weed seed uniformly into various soil aggregate classes, whereas with reduced tillage more seed accumulated in the unaggregated fraction of the soil. In the fall, weed seed distribution in relation to soil depth and among soil aggregate classes was similar for both tillage regimes.

Synopsis Growth of annual weeds increased markedly and bean yield reductions became more severe with soybean stands of less than 9 to 11 plants per foot of row. Bean yield reductions were more severe when weeds were left until or after stage 7 (early August). With moderate weed infestations and moisture deficits during the growing season, soybean yield reductions were less than with adequate moisture. Foxtail and smartweed infestations reduced bean yields about equally. Dry matter yields of above‐ground plant parts of soybeans and weeds together were slightly higher than that of weed‐free beans.

Synopsis In 15 experiments, yield reductions of soybeans in weed‐infested plantings averaged 3.7 bushels per acre or approximately 10% of weed‐free beans when weeds were grown the entire season. Foxtail reduced bean yields slightly less than smartweed or velvet leaf. Dry matter yield of above ground parts of soybeans and weeds combined approximated that of weed‐free beans alone. Effects of rainfall are discussed. Possible effects of uncontrolled factors are recognized.

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