Michael K. Hussey

Serial examination of the normal visual field using Octopus automated projection perimetry Evidence for a learning effect

Abstract. The influence of prior perimetric experience on the magnitude of both differential sensitivity and the short and long term fluctuations remains unclear, and confounds accurate interpretation of visual field data obtained by computer‐assisted perimetry. The purpose of the experiment was to identify and quantify any influence of training on the automated perimetric response. The full field of the right eye of 10 clinically normal, naive subjects was examined on 8 occasions with Octopus Program 21 (target size 3) on days 1–5 inclusive, 15, 16 and 44. Sensitivity increased with serial examination in 8 subjects. By dividing the field into zones, it was demonstrated that the learning effect was greatest in the superior field and for eccentricities beyond 30°.

Pointwise Univariate Linear Regression of Perimetric Sensitivity Against Follow-up Time in Glaucoma

PURPOSE The authors compared pointwise univariate linear regression (ULR) of sensitivity against follow-up as an indicator of visual field progression with that of the corresponding ULR of mean deviation (MD) and with the Glaucoma Change Probability (GCP) analysis. The authors determined the influence of the number and sequence of prior examinations on the slope of the pointwise function. METHODS Univariate linear regression was undertaken at each stimulus location on the arbitrarily assigned left eyes of 38 patients with glaucoma examined with the Humphrey Field Analyzer Programs 30-2 or 24-2 (stimulus size III, Humphrey Instruments Inc, San Leandro, CA). The mean age was 59.0 years (standard deviation [SD] = 12.9), the mean number of fields per patients was 12.0 (SD = 2.8), and the mean duration of follow-up was 6.0 years (SD = 1.6). RESULTS Four patients showed statistically significant MD slopes. Of the 34 patients exhibiting a nonsignificant MD slope, 15 exhibited clusters of at least two contiguous progressing locations. Less than half of these locations were designated as progressing by GCP. The GCP detected less than one third of the locations considered progressing by ULR for the last six fields in the series: this was attributed to the nonlinear nature of the decline in sensitivity. CONCLUSIONS The degree of agreement between the outcomes of ULR and GCP was dependent on the quality of the collected data, the magnitude of the baseline sensitivity, the extent and type of the subsequent visual field progression, and the position of the fields within the examination series. Good agreement was illustrated at those locations where the deterioration fell outside the limits of expected variability in stable glaucoma.

Projecting the right image: using projective techniques to measure brand image

Research has shown that consumers very often do not use explicit, concrete, rational factors to evaluate products, and thus their motivation to purchase is not always easy to articulate. Traditionally, marketers have used projective techniques in qualitative research groups to overcome this problem. This method is not infallible as each moderator brings his or her own style to discussions and subjective judgement to the interpretation of results, and it is practically impossible to replicate identically over time. The work presented in this paper describes the development of a set of implicit characteristics for two animation sets to which respondents will respond similarly and with consistency, through which we can identify the brand image held and consequently the motivations behind brand choice.

Using the Concept of Loss: An Alternative SERVQUAL Measure

(1999). Using the Concept of Loss: An Alternative SERVQUAL Measure. The Service Industries Journal: Vol. 19, No. 4, pp. 89-101.

The diffusion of quantitative methods into marketing management

Investigates the extent to which various quantitative techniques are employed in marketing across Europe. Marketing practitioners, marketing services providers and marketing educators were all surveyed in a pan‐European study aimed at uncovering the extent of diffusion into practice of quantitative methods. Finds that, despite the increased use of computers, and the wider availability of modelling software, the most popular quantitative techniques are still the most basic data summary and presentation methods. Marketing students receive only a limited exposure to advanced quantitative methods and practitioners typically find little use for the more sophisticated techniques.

Quantitative methods in marketing: The multivariate jungle revisited introduction and overview to special edition

This introductory article provides an overview of the varied and interesting contributions that follow. Certain key themes are identified which include the importance of graphical methods for communicating the information content of data and the impact of increased desktop computing power on the marketing managers ability to work with quantitative models. Finally, a set of rules or commandments are included which aim to help the marketing professional avoid the more common pitfalls of quantitative analysis.

The quantification of the visual field in computer-assisted threshold perimetry

Computer simulations were carried out to investigate the suitability of the Monte Carlo technique as a means for deriving the integral of sensitivity as measured over the three-dimensional surface area and thus providing a quantitative expression of the visual field. The simulations were based upon the standard normal data of Octopus programs 21 and 31 and upon age matched data for the central 30° threshold program of the Dicon AP3000. In addition, the sensitivity values at each eccentricity derived by the Octopus were also weighted for the product of retinal ganglion cell receptive field density and spatial summation and a further integration carried out. The indices for various types of field loss are illustrated.