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Biomedical subjects

T P Hutchinson

Publications and source records attributed to T P Hutchinson.

At least 19 recordsLinked to original sources
PubMed2004

Analysis of datasets showing which compounds kill which organisms: inferring two systems.

Experiments are sometimes conducted to show which of several compounds is successful at inactivating which of several microorganisms. This paper proposes a method of analysing the datasets obtained. The example refers to 33 compounds (2,4-dihydroxythiobenzanilides) and seven microorganisms (dermatophytes) [data from Eur. J. Med. Chem. 35 (2000) 393]. The conclusion is that two systems or modes of action are needed to explain the data.

Anilides↗
PubMed2003

Agreement between experts: an answer, but is it the answer for you?

The question of how should agreement between experts be measured, when their opinions are expressed on an ordinal scale, is discussed. The example used is that of quality of articles submitted to Journal of Clinical Neuroscience. Polychoric correlation is a useful concept, and there are now computer programs available to estimate this. However, it is also emphasised that the definition of agreement is a matter of choice, and the choice should be made carefully: even error-free measurements should not automatically be assumed to possess all the properties of numbers, and ordinal categories bring further difficulties.

Data Interpretation, Statistical↗
PubMed2003

Statistics and graphs for heart rate variability: pNN50 or pNN20?

Two measures of heart rate variability, pNN50 and pNN20, are compared. A non-linear transformation of these measures is proposed, that is helpful in understanding their interrelationship. Provided a valid statistical test is employed, results from analysing pNN20 are likely to be equivalent to those from analysing pNN50. Arguments recently made by Mietus et al (2002 Heart 88 378-80) against the commonly used pNN50 are unconvincing.

Data Interpretation, Statistical↗
PubMed2002

Should we routinely test for simultaneous location and scale changes?

It is argued that in many circumstances, there is no compelling reason to believe that measurements from several experimental groups have the same variability. If it is plausible that the variabilities may differ, a statistical test sensitive to changes of scale as well as to changes of location should be selected. Some references to such tests are given.

Data Interpretation, Statistical↗
PubMed2001

Partial knowledge and answer-until-correct tasks in birds and humans.

Jolliffe and Jolliffe (1997, Biometrics 53, 1136-1142) and Ridout (1999, Biometrics 55, 660-662) have proposed models applicable to memory in coal tits. It is now argued that the birds' task is analogous to answer-until-correct tests used in educational settings in humans, and models from the latter context may be used with the birds' data.

Animals↗
PubMed2000

Graphing the death of Escherichia coli.

The graphical presentation of measurements of the progress over time of bacterial death or inactivation is discussed. Specifically, the Weibull distribution may be a useful generalisation of the exponential distribution. Data from experiments on the non-thermal death of Escherichia coli reported by Shadbolt et al. [Int. J. Food Microbiol. 49 (1999) 129] are reexamined to support this claim.

Escherichia coli↗
PubMed1999

Familial association of disease and the structure of trivariate distributions.

In its usual form, the multifactorial model of disease transmission assumes that the liabilities to disease have a multivariate normal distribution. This paper studies how sensitive to this assumption are the quantitative results from the model. Accordingly, bounds are established for the probability of a child having a disease, given that both parents have it and taking the heritability of the disease to be known. Unfortunately, these bounds turn out to be wide. For example, a probability that is 0.38 under the trivariate normal model may be as low as 0.12 or as high as 0.78 under other trivariate models, even if attention is restricted to those of variables-in-common form. The broader statistical issue of the meaning of trivariate dependence, as distinct from bivariate dependence, is also discussed.

Adult↗
PubMed1998

On a recognition task in which some distractors were half-familiar.

Models are suggested for the task of recognizing word-pairs, where the distractors may be pairs of new words, or may be a new word paired with a previously-seen word. These models are relevant to an experiment recently reported by Isingrini et al., and suggest rather different conclusions to theirs--namely, that the elderly differ from the young in both learning and response selection.

Humans↗