The use of spermicide containing nonoxynol-9 in the prevention of HIV infection.
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HIV Infections↗
Biomedical subjects
K D Bird
Publications and source records attributed to K D Bird.
Sex differences in suicidal behaviour of referred adolescents.
Reports of suicidal behaviour from four countries using the same measures were higher for girls than for boys, and higher in self-reports than in parent reports for both referred and normal adolescents. In a sample of 480 referred adolescents, patterns of 'low' and 'high' suicidal scores were different when age, sex and diagnosis were considered. The probability of high scores for girls showed only a marginal increase with age, while there was a striking rise for boys. An affective diagnosis doubled the probability of high scores for both boys and girls, while it had no effect on low scores. Psychosocial stressors also increased the probability of high suicidal scores, particularly in adolescents with an affective disorder. Sex differences in suicidal behaviour were marked in the low-scoring groups.
Adolescent↗
The effects of orally administered delta 9-tetrahydrocannabinol in man on mood and performance measures: a dose-response study.
A dose-response study of the effect of orally administered delta 9-tetrahydrocannabinol (THC) on human mood and skills performance was conducted. Using five dose levels of THC (0, 5, 10, 15, 20 mg) with 16 volunteers per dosage group, mood and performance measures were recorded at five testing occasions, one before and four after drug administration. The slope of the linear regression of performance on the test battery was significant for up to 200 minutes after dosage. That is to say, oral THC, at the doses used, produced significant dose-dependent impairment of performance for a period in excess of three hours. A similar time course for the effect of THC on the subjective assessment of intoxication ('stone') suggested a correlation between drug-induced impairment skills and the effects on mood.
Administration, Oral↗
Simultaneous multiple comparison procedures in psychiatric research.
The multiple comparison problem arises in any research design in which the scores of more than two groups are compared on a single dependent variable. The analysis of variance provides a way of testing the null hypothesis that all population means are equal with a type 1 error rate of alpha. When the joint null hypothesis is accepted, the outcome of such a test is unambiguous: all population means are equal. When the null hypothesis is rejected, ANOVA is insufficient to identify the pattern of departure from equality. The Scheffe procedure can be used to test any number and type of contrast that is suggested by an inspection of the data. It ensures that the chance of incorrectly rejecting one or more hypotheses in the set so tested cannot exceed alpha. Contrasts between the population means which are specified independently of the data can be tested using Bonferroni-adjusted t tests to control the experimentwise error rate. Factorial ANOVA designs can also be analysed by testing linear contrasts. If a researcher has definite expectations about the pattern of mean differences, he can test a set of planned contrasts with a familywise error rate (if contrasts are written within main effects and interaction effects) or an EER. If he is uncertain about which hypotheses to test, post hoc procedures which are modifications of the Scheffe technique can be used.
Analysis of Variance↗
Simultaneous multiple comparison procedures for categorical data.
Methods are outlined for performing simultaneous multiple comparisons between groups when the dependent variable is one in which subjects are assigned to one of two or more categories. These methods provide tests which are analogous to Scheffe- and Bonferroni-adjusted tests of contrasts in the analysis of variance. Examples are provided of each of these procedures.
Analysis of Variance↗
Statistical power in psychiatric research.
Statistical power is neglected in much psychiatric research, with the consequence that many studies do not provide a reasonable chance of detecting differences between groups if they exist in the population. This paper attempts to improve current practice by providing an introduction to the essential quantities required for performing a power analysis (sample size, effect size, type 1 and type 2 error rates). We provide simplified tables for estimating the sample size required to detect a specified size of effect with a type 1 error rate of alpha and a type 2 error rate of beta, and for estimating the power provided by a given sample size for detecting a specified size of effect with a type 1 error rate of alpha. We show how to modify these tables to perform power analyses for multiple comparisons in univariate and some multivariate designs. Power analyses for each of these types of design are illustrated by examples.
Clinical Trials as Topic↗
The effect of cannabidiol, alone and in combination with ethanol, on human performance.
Fifteen volunteers received cannabidiol (CBD) (320 microgram/kg) or placebo (both orally, T0), and 60 min later they consumed an ethanolic beverage (0.54 g/kg) or placebo. The effects were measured at T1 (100 min after CBD ingestion), T2 (160 min) and T3 (220 min) using cognitive, perceptual and motor function tests. Factorial analysis indicated that test procedures could be adequately expressed by three rotated factors: A reaction speed factor (I), a standing steadiness factor (II) and a psychomotor coordination/cognitive factor (III). Ethanol produced a significant decrement in factor III. There was no demonstrable effect of CBD, either alone or in combination with ethanol. Neither CBD nor ethanol produced any significant effect on pulse rate. Prior administration of CBD did not significantly affect the blood ethanol levels. Whilst the subjects were able to identify correctly when they were given ethanol, they did not report any subjective effects of CBD.
Adolescent↗
The effect of (-) trans-delta9-tetrahydrocannabinol, alone and in combination with ethanol, on human performance.
Twenty five volunteers received (-) trans-delta9-tetrahydrocannabinol (THC) (320 microgram/kg) or placebo (both orally, T0), and, 60 min later, they consumed an ethanolic beverage (0.54 g/kg) or placebo. The effects of this medication were measured at T1 (100 min after THC ingestion), T2 (160 min), T3 (220 min) and T4 (280 min) using a battery of cognitive, perceptual and motor function tests. Factorial analysis indicated that the test procedures could be adequately expressed by four rotated factors: a reaction speed factor (I'), a cognitive factor (II'), a standing steadiness factor (III') and a psychomotor coordination factor (IV'). The first principal component (I) was used as a measure of general performance across the whole test battery. Both THC and ethanol produced significant decrements in the general performance factor. Ethanol produced significant decrements in standing steadiness and psychomotor coordination, while THC caused a significant deterioration in performance on all the four rotated factors. In all cases the peak effect of ethanol occurred at T1 and by T4 the effect had worn off. The performance decrements induced by THC were slower in onset and lasted longer than those induced by ethanol. In general, the peak effect of THC occurred at T1 and T2. There was no evidence of any interaction between THC and ethanol, and the effects of a combination of THC and ethanol were no more than additive. THC (but not ethanol) produced a significant rise in pulse rate. Prior administration of THC did not significantly affect the blood ethanol levels obtained. The subjects were able to identify correctly which of the treatments they had received.
Adolescent↗