Biomedical subjects

D M Berridge

Publications and source records attributed to D M Berridge.

5 recordsLinked to original sources

PubMed2000

A continuation ratio random effects model for repeated ordinal responses.

This paper presents methods of analysis for ordinal repeated measures. We use a generalization of the continuation ratio model with a random effect. We handle frailty by using a normal distribution and also a non-parametric distribution. The methodology is readily implemented in existing software and flexible enough to treat large data sets with uncommon time measurements as well as different numbers of repeated measures for each individual. The models are used to investigate how a group of explanatory variables influences the overall condition of patients treated for breast cancer.

Age Factors↗

PubMed1998

Saccadic eye movements in families multiply affected with schizophrenia: the Maudsley Family Study.

OBJECTIVE: Family studies have shown that abnormalities of smooth pursuit eye movement are increased in the adult relatives of schizophrenic probands as well as in the probands themselves. More recently, an inability of schizophrenic subjects to inhibit reflexive saccades reliably has been shown. This study aimed to test the hypothesis that the latter dysfunction is part of the extended schizophrenia phenotype. METHOD: With the use of infrared oculography, measurements of reflexive saccades and antisaccades were undertaken in 29 probands with schizophrenia, 50 of their nonpsychotic first-degree relatives, and 38 unrelated healthy volunteers. RESULTS: Probands, relatives, and healthy subjects showed no overall differences in the generation of reflexive saccades. However, in the antisaccade task, probands showed more saccadic distractibility when they were required to inhibit reflexive saccades. Analysis of corrective saccades showed that this was not due to failed comprehension or motivation. Relatives of the probands with high saccadic distractibility showed a higher distractibility rate than relatives of the probands with normal distractibility. Across all subjects, females showed a higher rate of distractibility errors than males. CONCLUSIONS: The ability to suppress reflexive saccades is an objective neurocognitive measure that is impaired in schizophrenic patients and in a proportion of their biological relatives. This antisaccade abnormality may be a vulnerability marker in a subset of schizophrenic patients and their families.

Adult↗

PubMed1996

An application of a marked point process in pre-clinical medicine.

Several authors have employed marked point processes to model complex survival time data. In this paper it is proposed to illustrate further the flexibility of marked point processes by using such a framework to model pre-clinical data which comprise survival times accompanied by ordinal outcomes.

Adrenal Glands↗

PubMed1996

Social influences on false belief access: specific sibling influences or general apprenticeship?

Some recent studies have found a relation between the number of siblings 3-4-year-old children have and their performance on false belief tasks. 2 experiments reported here examine a variety of factors in children's social environments, including daily contact with peers and adults as well as the numbers of their siblings, on a battery of false belief tests. In Experiment 1, 82 preschoolers were studied in Rethymnon, Crete, in order to obtain a range of extended kin available as a resource for the child. In Experiment 2, 75 Cypriot preschoolers were studied in Nicosia in order to examine the influences of each child's daily social contacts, as measured by maternal questionnaire. Logistic regression revealed that the factors which account for most of the predicted variance on the theory of mind tests were (a) the number of adult kin available (Experiment 1) or adults interacted with daily (Experiment 2), (b) the child's age, (c) the number of older siblings a child has, and (d) the number of older children interacted with daily. The results suggested that theory of mind is not simply passed from one sibling to another in a process of social influence. It seems more likely that a variety of knowledgeable members of her or his culture influence the apprentice theoretician of mind.

Age Factors↗

PubMed1991

Analysis of failure time data with ordinal categories of response.

When failure times are observed, additional information concerning the type of failure is often recorded. A method which simultaneously models the failure times and additional information in the form of ordinal categories is discussed. An application to clinical trial data, in which the failure times are times of onset of headache, and the headaches are classified into the ordinal categories mild, moderate and severe, illustrates how this method may be used and how the final model can be interpreted. The continuation ratio model, which is used in this method, is described in detail.

Clinical Trials as Topic↗