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Biomedical subjects

A F Monk

Publications and source records attributed to A F Monk.

11 recordsLinked to original sources
PubMed2001

Statistical assessment of the learning curves of health technologies.

OBJECTIVES: (1) To describe systematically studies that directly assessed the learning curve effect of health technologies. (2) Systematically to identify 'novel' statistical techniques applied to learning curve data in other fields, such as psychology and manufacturing. (3) To test these statistical techniques in data sets from studies of varying designs to assess health technologies in which learning curve effects are known to exist. METHODS - STUDY SELECTION (HEALTH TECHNOLOGY ASSESSMENT LITERATURE REVIEW): For a study to be included, it had to include a formal analysis of the learning curve of a health technology using a graphical, tabular or statistical technique. METHODS - STUDY SELECTION (NON-HEALTH TECHNOLOGY ASSESSMENT LITERATURE SEARCH): For a study to be included, it had to include a formal assessment of a learning curve using a statistical technique that had not been identified in the previous search. METHODS - DATA SOURCES: Six clinical and 16 non-clinical biomedical databases were searched. A limited amount of handsearching and scanning of reference lists was also undertaken. METHODS - DATA EXTRACTION (HEALTH TECHNOLOGY ASSESSMENT LITERATURE REVIEW): A number of study characteristics were abstracted from the papers such as study design, study size, number of operators and the statistical method used. METHODS - DATA EXTRACTION (NON-HEALTH TECHNOLOGY ASSESSMENT LITERATURE SEARCH): The new statistical techniques identified were categorised into four subgroups of increasing complexity: exploratory data analysis; simple series data analysis; complex data structure analysis, generic techniques. METHODS - TESTING OF STATISTICAL METHODS: Some of the statistical methods identified in the systematic searches for single (simple) operator series data and for multiple (complex) operator series data were illustrated and explored using three data sets. The first was a case series of 190 consecutive laparoscopic fundoplication procedures performed by a single surgeon; the second was a case series of consecutive laparoscopic cholecystectomy procedures performed by ten surgeons; the third was randomised trial data derived from the laparoscopic procedure arm of a multicentre trial of groin hernia repair, supplemented by data from non-randomised operations performed during the trial. RESULTS - HEALTH TECHNOLOGY ASSESSMENT LITERATURE REVIEW: Of 4571 abstracts identified, 272 (6%) were later included in the study after review of the full paper. Some 51% of studies assessed a surgical minimal access technique and 95% were case series. The statistical method used most often (60%) was splitting the data into consecutive parts (such as halves or thirds), with only 14% attempting a more formal statistical analysis. The reporting of the studies was poor, with 31% giving no details of data collection methods. RESULTS - NON-HEALTH TECHNOLOGY ASSESSMENT LITERATURE SEARCH: Of 9431 abstracts assessed, 115 (1%) were deemed appropriate for further investigation and, of these, 18 were included in the study. All of the methods for complex data sets were identified in the non-clinical literature. These were discriminant analysis, two-stage estimation of learning rates, generalised estimating equations, multilevel models, latent curve models, time series models and stochastic parameter models. In addition, eight new shapes of learning curves were identified. RESULTS - TESTING OF STATISTICAL METHODS: No one particular shape of learning curve performed significantly better than another. The performance of 'operation time' as a proxy for learning differed between the three procedures. Multilevel modelling using the laparoscopic cholecystectomy data demonstrated and measured surgeon-specific and confounding effects. The inclusion of non-randomised cases, despite the possible limitations of the method, enhanced the interpretation of learning effects. CONCLUSIONS - HEALTH TECHNOLOGY ASSESSMENT LITERATURE REVIEW: The statistical methods used for assessing learning effects in health technology assessment have been crude and the reporting of studies poor. CONCLUSIONS - NON-HEALTH TECHNOLOGY ASSESSMENT LITERATURE SEARCH: A number of statistical methods for assessing learning effects were identified that had not hitherto been used in health technology assessment. There was a hierarchy of methods for the identification and measurement of learning, and the more sophisticated methods for both have had little if any use in health technology assessment. This demonstrated the value of considering fields outside clinical research when addressing methodological issues in health technology assessment. CONCLUSIONS - TESTING OF STATISTICAL METHODS: It has been demonstrated that the portfolio of techniques identified can enhance investigations of learning curve effects. (ABSTRACT TRUNCATED)

Cholecystectomy↗
PubMed2000

Assessment of the learning curve in health technologies. A systematic review.

OBJECTIVE: We reviewed and appraised the methods by which the issue of the learning curve has been addressed during health technology assessment in the past. METHOD: We performed a systematic review of papers in clinical databases (BIOSIS, CINAHL, Cochrane Library, EMBASE, HealthSTAR, MEDLINE, Science Citation Index, and Social Science Citation Index) using the search term "learning curve." RESULTS: The clinical search retrieved 4,571 abstracts for assessment, of which 559 (12%) published articles were eligible for review. Of these, 272 were judged to have formally assessed a learning curve. The procedures assessed were minimal access (51%), other surgical (41%), and diagnostic (8%). The majority of the studies were case series (95%). Some 47% of studies addressed only individual operator performance and 52% addressed institutional performance. The data were collected prospectively in 40%, retrospectively in 26%, and the method was unclear for 31%. The statistical methods used were simple graphs (44%), splitting the data chronologically and performing a t test or chi-squared test (60%), curve fitting (12%), and other model fitting (5%). CONCLUSIONS: Learning curves are rarely considered formally in health technology assessment. Where they are, the reporting of the studies and the statistical methods used are weak. As a minimum, reporting of learning should include the number and experience of the operators and a detailed description of data collection. Improved statistical methods would enhance the assessment of health technologies that require learning.

Biomedical Technology↗
PubMed2000

Where am I looking? The accuracy of video-mediated gaze awareness.

Participants worked in pairs, with one person gazing at a flat horizontal stimulus between them. The other participant estimated where the gazer was looking. Experiment 1 used linear scales as gaze targets. The mean root mean square error of estimation equates to 3.8 degrees of head-and-eye pan and 2.6 degrees of tilt. This small error of estimation was essentially the same in a video-mediated condition and in one in which a procedure that did not allow the estimator to see the head-and-eye movement to the target position was used. Experiment 2 obtained comparable gaze estimation performance in face-to-face and video-mediated conditions, using a combined pan-and-tilt grid. It is concluded that people are very good at estimating what someone else is looking at and that such estimations should be practical during video-mediated conversation.

Adult↗
PubMed1999

Telemedicine. What happens in remote consultation.

The results of a field study of three sites that used video to link primary care medical centers to hospitals are reported. The analysis was concerned with identifying the people involved, the tasks carried out in collaboration at each end of the link, and how the different communications facilities helped or hindered. The results are summarized as six task characteristics and their design implications for this model of telemedical consultation are discussed.

Communication↗
PubMed1998

Reasoning about tasks, activities and technology to support collaboration.

An aspect of collaboration described as 'semi-synchronized activity' is discussed as a particular challenge for the task analysis (TA) of collaborative work. TA typically involves the decomposition of work systems into essentially independent component processes between which commodities (information or materials) pass. In collaborative work, people routinely violate the condition of independence by moving seemlessly in and out of synchronization with one another, allowing for both independent and varying levels of conjoint activity. The shift between joint and independent projects is not fixed but managed through more or less explicit awareness of the other people over time. A number of case studies of the effect of communication technologies in telemedical consultation are drawn upon to illustrate the relationship between awareness and synchronization in collaborative work. They show that an analysis of collaborative activity requires a consideration of: (1) the activities constituting work; (2) the interactions between participants required to carry out the activities; (3) who else has access to these activities besides the primary participants in the ongoing work; (4) the contemporaneity of activities; (5) the locations/environments in which the activities are carried out; and (6) the constraints that apply to accessibility and participation within and between these environments. The Comms Usage Diagram is described as a framing notation incorporating these characteristics for a broad, communications-level analysis of collaborative activity. It shows how particular technologies relate to particular phases of work, indexing their effects to collaborative activities in those contexts.

Humans↗
PubMed1993

Perceptual grouping in visual word recognition.

Four experiments are presented in which printed texts are read for their meaning. Some of the texts were mutilated by altering the size of selected letters. In Experiments 1, 2, and 3, the number of words mutilated per passage and the number of letters changed per word were both manipulated. In all three experiments, reading was slowed as a function of the number of words changed per passage, while the number of letters changed per word had a much smaller effect. The interaction between the number of words and number of letters changed was not significant in any of the experiments. It is difficult to explain these results merely in terms of changes in the discriminability of letters. In Experiment 2 all uppercase text was used, which argues against an explanation in terms of supraletter features such as word envelope. We propose an explanation in terms of visual attention and the perceptual grouping required prior to feature recognition. The last experiment supports this explanation through the counterintuitive finding that adding letters of intermediate size can improve legibility by allowing grouping processes to associate large and small letters as belonging to the same word object.

Adult↗
PubMed1983

Evidence for distinct verbal memory pathologies in severely and mildly disturbed schizophrenics.

It is well known that schizophrenics have difficulty in effectively encoding verbal materials into their long-term memories and consequently show a deficit in recall. Recently, orienting tasks were introduced as a method for achieving equivalent to normal encoding and mnemonic organization in schizophrenics; consequently, their deficit in recall disappeared. A detailed review of the literature, however, showed that such effective orienting tasks had only been applied to mildly disturbed schizophrenics (nonchronic, in a good condition). This report presents three experiments which show that more severely disturbed (chronic, hospitalized) schizophrenics, unlike mildly disturbed patients, have memory deficits that cannot be located at the encoding stage. Severely disturbed schizophrenics show (1) a recall deficit, even after effective encoding and mnemonic organization are induced; (2) excessive forgetting over 24- and 48-hour periods; and (3) a recognition memory deficit. These deficits are in addition to their encoding deficit. The use of a matched-tasks check in experiments 2 and 3 suggests that this postencoding deficit is a differential deficit and does not is a differential deficit and does not simply reflect the schizophrenic generalized deficit. Theoretical implications, also supported by the use of various organizational indices (e.g., clustering, hierarchical clustering schemes, and hierarchical grouping analysis), are discussed.

Adult↗
PubMed1980

Sorting consistency as a diagnostic tool for schizophrenics and normals.

This report demonstrates the potential of the Sorting Consistency Task, both for assessing the degree of schizophrenic disturbance in patients, and for screening normals for schizophrenic tendencies. The task can be administered quickly and adapted for individual or group testing. Experiment 1 demonstrated a strong relationship between the Sorting Consistency Task and indicators of schizophrenic disturbance. Experiment 2 used normals and demonstrated that the Sorting Consistency Task could discriminate between subjects who score high or low on the Physical Anhedonia Scale of Chapman et al. (1976).

Adult↗