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Antimicrobial drugs have played an indispensable role in decreasing illness and death associated with infectious diseases in animals and humans. However, selective pressure exerted by antimicrobial drug use also has [...]

Five years after the Three Mile Island nuclear accident, the mental health of women who had been pregnant and living within 10 miles of Three Mile Island at the time of the accident was similar to that of women from the same area who became pregnant after the accident. Ratings of the development of the two groups of children when they were 5 years old were also similar. However, women who were pregnant during the crisis and had been extremely disturbed' about their pregnancies rated their children's health as poorer than did the women who were pregnant later. (Am J Public Health 1991; 81:384-386), Pregnant women, or those with young children, who lived near the Three Mile Island (TMI) nuclear facility experienced considerable psychological distress after the accident in 1980. A subsequent study indicated little biological consequences of the accident for the children, however. To evaluate the long-term psychological and physical effects of the TMI crisis, a random sample of people living within 10 miles of the facility were interviewed. Mothers and children (1,833 pairs) for whom birth occurred within 12 months after the accident made up the study group, while pairs (1,808) who gave birth 13 to 24 months after the accident formed the control group. Of interest were the number of physician visits, the children's developmental profiles, scores on tests suggesting emotional problems, maternal anxiety and depression, and mothers' impressions of their own and their children's health. Results showed a trend toward poorer status for the study group for all factors evaluated, but the only variable for which the study and control groups differed significantly was the study group mothers' more negative ratings of their children's health. Seven percent fewer mothers in this group than in the control group rated their children's health as ''excellent''. Mothers who rated their children's health as poorest were those who reported feeling the most disturbed shortly after the children's births. In general, the results show only small differences between the study and control groups, with perhaps the strongest effect found among those who were most disturbed. Follow-up studies will evaluate whether the children of these mothers were, in fact, in poorer health, or whether their mothers paid more attention to their health than the less disturbed parents. (Consumer Summary produced by Reliance Medical Information, Inc.)

Typically, investigations are conducted with the goal of generating inferences about a population (humans or animal). Since it is not feasible to evaluate the entire population, the study is conducted using a randomly selected subset of that population. With the goal of using the results generated from that sample to provide inferences about the true population, it is important to consider the properties of the population distribution and how well they are represented by the sample (the subset of values). Consistent with that study objective, it is necessary to identify and use the most appropriate set of summary statistics to describe the study results. Inherent in that choice is the need to identify the specific question being asked and the assumptions associated with the data analysis. The estimate of a "mean" value is an example of a summary statistic that is sometimes reported without adequate consideration as to its implications or the underlying assumptions associated with the data being evaluated. When ignoring these critical considerations, the method of calculating the variance may be inconsistent with the type of mean being reported. Furthermore, there can be confusion about why a single set of values may be represented by summary statistics that differ across published reports. In an effort to remedy some of this confusion, this manuscript describes the basis for selecting among various ways of representing the mean of a sample, their corresponding methods of calculation, and the appropriate methods for estimating their standard deviations. [ABSTRACT FROM AUTHOR]