Quantitative data validation (automated visual evaluations).

Historically, validation has been perfonned on a case study basis employing visual evaluations, gradually inspiring confidence through continual application. At present, the method of visual evaluation is the most prevalent form of data analysis, as the brain is the best pattern recognition device known. However, the human visual/perceptual system is a complicated mechanism, prone to many types of physical and psychological influences. Fatigue is a major source of inaccuracy within the results of subjects perfonning complex visual evaluation tasks. Whilst physical and experiential differences along with age have an enormous bearing on the visual evaluation results of different subjects. It is to this end that automated methods of validation must be developed to produce repeatable, quantitative and objective verification results. This thesis details the development of the Feature Selective Validation (FSV) method. The FSV method comprises two component measures based on amplitude differences and feature differences. These measures are combined employing a measured level of subjectivity to fonn an overall assessment of the comparison in question or global difference. The three measures within the FSV method are strengthened by statistical analysis in the form of confidence levels based on amplitude, feature or global discrepancies between compared signals. Highly detailed diagnostic infonnation on the location and magnitude of discrepancies is also made available through the employment of graphical (discrete) representations of the three measures. The FSV method also benefits from the ability to mirror human perception, whilst producing infonnation which directly relates human variability and the confidence associated with it. The FSV method builds on the common language of engineers and scientists alike, employing categories which relate to human interpretations of comparisons, namely: 'ideal', 'excellent', 'very good', 'good', 'fair', 'poor' and 'extremely poor' . Quantitative Data Validation Automated Visual Evaluations II Anthony John Michael Martin PhD Thesis ACKNOWLEDGEMENTS My thanks go to my supervisor and mentor Dr. Alistair Duffy for his enduring opinions, encouragement, guidance and continual support. I gratefully acknowledge the invaluable help of the following people in the preparation of this thesis: Dr. Celine Turner, Paul Cartright, Trevor Benson and Malcolm Woolfson. Special thanks go to my parents and my fiancee for their support. Without their patience this thesis would not have been possible. Quantitative Data Validation Automated Visual Evaluations III Anthony John Michael Martin PhD Thesis CONTENTS