“Loss to follow-up” can be substantial in substance abuse clinical trials. When extensive losses to follow-up occur, one must cautiously analyze and interpret the findings of a research study. Aims of this project were to introduce the types of missing data mechanisms and describe several methods for analyzing data with loss to follow-up. Furthermore, a simulation study compared Type I error and power of several methods when missing data amount and mechanism varies. Methods compared were the following: Last observation carried forward (LOCF), multiple imputation (MI), modified stratified summary statistics (SSS), and mixed effects models. Results demonstrated nominal Type I error for all methods; power was high for all methods except LOCF. Mixed effect model, modified SSS, and MI are generally recommended for use; however, many methods require that the data are missing at random or missing completely at random (i.e., “ignorable”). If the missing data are presumed to be nonignorable, a sensitivity analysis is recommended.

Thirteen June bearing cultivars and twelve Maryland-USDA breeding program selections were tested in the south central Missouri Ozark region during the 1986-1989 seasons. Production was on ground level matted rows at 24 in (61 cm) by 42 in (107 cm) spacing. The highest yielding cultivars and selections were ‘Earliglow,’ MDUS 5076 (early); ‘Kent,’ ‘Honeoye,’ ‘Redchief’ (early-midseason); MDUS 5084, ‘Allstar,’ ‘Jewel,’ ‘Lester,’ (late-midseason); and MDUS 4740, ‘Delite’ (late). ‘Earliglow,’ ‘Honeoye,’ ‘Allstar,’ and ‘Delite’ yielded 30% less than in a previous station trial (three year average). This was due primarily to blossom mortality that occurred because of the lack of irrigation for frost control, Disease ratings showed no clear trends.

The victorian study of single vehicle rural accidents was a joint initiative of the victorian road traffic authority, road construction authority and the transport accident commission. The aim of the project was to increase understanding of single vehicle accidents, particularly the roles of roadside objects, vehicle speed and driver fatigue in such accidents. The factors identified as most commonly contributing to accidents were trees close to the traffic lanes and the presence of unsealed shoulders. Driver fatigue was also identified as a major problem. (Author/TRRL)