Reference intervals (RIs) are sets of percentiles that outline the range of laboratory test results belonging to healthy individuals. They are essential for the interpretation of laboratory test results. A wide variety of factors affect the validity of RIs. Among them are the statistical methods used to estimate RIs. However, little investigation has gone into the effect that different statistical methods have on the resulting RIs. This is particularly needed as the complexity of paediatric data makes it difficult to estimate RIs. These difficulties, however, can be addressed using appropriate statistical techniques, provided that there is an outline of scenarios under which these techniques are truly “appropriate”. The objective of this thesis is to provide a thorough investigation into the effect of different statistical methods on RIs. A systematic review was first conducted with a focus on paediatric RIs. The results of this review revealed that critical analysis steps are often overlooked due to complicated paediatric data. Even though a guideline addressing the establishment of RIs is available, there is great heterogeneity in the statistical methods chosen to estimate paediatric RIs. An extensive simulation involving the three most commonly used approaches to estimate RIs (the parametric, non-parametric, and robust methods) was also conducted to investigate and compare the performance of the different methods. The simulation results show that, when data follows a Gaussian distribution, or close to it, the parametric method provides the best estimates. The non-parametric method did not provide the best estimates of RIs (compared to the parametric method) unless data was highly skewed and/or large sample sizes were used. In addition, the bias and MSE associated with the parametric method when data follows a Gaussian distribution was mathematically derived, which may lead to the development of a bias corrected and more precise approach in the future. / Thesis / Master of Science (MSc)

Reference intervals are important estimates used to determine whether an individual is healthy or unhealthy. They are the most widely used decision making tool in medicine and heavily influence doctor’s decisions regarding patient care. Despite the abundance of reference interval research in the field of clinical chemistry, age-related reference intervals have yet to be well-established for elderly populations. Many physiological and biochemical changes have been documented to occur with age however limited attempts have been made to quantify these changes. As a result, it is typical in clinical practice to assess geriatric patient data using an adult reference interval. Such practices can result in over-medicalization, unnecessary medical procedures and/or missed diagnoses. This thesis aims to address this gap in literature by summarizing what geriatric reference intervals are available and by investigating how reference intervals are affected by the presence of morbidity, a common characteristic of the elderly. The first chapter of the thesis introduces the reader to reference intervals, summarizes the current guidelines used in their determination and provides a rationale for the use of age-related reference intervals in geriatrics. Chapter 2 presents a systematic review that summarizes all available reference intervals for populations ≥65 years of age and the methodology used in their determination. Despite extreme variability in methodology, evidence suggests that geriatric reference intervals are significantly different from those of adults for many analytes. Chapter 3 presents a study that evaluates the effect morbidity has on reference intervals. In this study data from the National Health and Nutrition Examination Survey (NHANES) was used to calculate age-specific reference intervals for creatinine, a marker of kidney function known to increase with age. Findings suggest that the presence of morbidity significantly increases the upper limit for creatinine in elderly populations. Finally, the concluding chapter summarizes the overall findings of the thesis, proposes areas for future research and reinforces the importance of the above findings. / Thesis / Master of Science (MSc) / Reference intervals are estimates used to determine whether an individual is healthy or unhealthy. In particular this thesis investigates reference intervals for blood test results. Currently no age-specific reference intervals for the elderly are used clinically, instead the normalcy of a blood test result for an elderly person is based on adult reference intervals. This process may lead to over-medicalization or missed diagnoses in geriatrics. Within this thesis is a systematic review of the literature that was performed to capture any available reference intervals that have been published for populations greater than 65 years of age. It was determined that a multitude of geriatric reference intervals are available in literature but they are not used clinically and have no standardized methodology for their determination. Despite this lack of standardization, studies proved that geriatric reference intervals are significantly different from those of adult populations. Given that morbidity or the presence of disease is common in older patients it was suspected this may be a reason for the difference in reference intervals. A separate study was then performed to determine whether the presence of disease affects reference interval calculations. Results from this study showed that the presence of disease affects reference intervals in older individuals more so than younger individuals.

Objectives: Phase 1) Establish echocardiographic reference intervals for measurements of the normal canine right heart. Phase 2) Describe the repeatability of normal right heart echocardiographic measurements. Phase 3) Describe the repeatability of right heart echocardiographic measurements which predict pulmonary artery pressure. Materials and Methods: Phase 1) 45 healthy adult dogs. Dogs underwent one echocardiographic examination by the same operator. Phase 2) 6 randomly selected dogs from the pool of Phase 1 dogs. Dogs underwent repeated echocardiograms by two operators. Phase 3) 4 client-owned dogs. Dogs underwent repeated echocardiographic examination by two operators. Results: Phase 1) The linear relationship between dimension and transformed body weight was highly variable. For linear dimensions, most of the scaling exponents were close to the theoretical value of 1/3. For area measurements, most of the scaling exponents were close to 2/3. Phase 2) Of the 168 within-day, between-day and between-operator coefficients of variation (CV) generated, 154 (91.7%) were below 15% and 135 (80.4%) were less than 10%. Phase 3) Of the 100 within-day, between-day and between-operator CVs generated, 72 (72%) were below 20% and 46 (46%) were below 10%. Conclusions: The right heart can be measured with relatively low repeatability. Measurement of the tricuspid regurgitation velocity should be the first priority when attempting to predict pulmonary artery pressure. If tricuspid regurgitation is not present, the use of transpulmonic acceleration time (AT) and the ratio of transpulmonic acceleration-to-ejection time (AT:ET) to indirectly assess pulmonary artery pressure is recommended. / Master of Science

No / Facial expressions have been studied looking for its diagnostic capabilities in mental health and clues for longevity, gender and other such personality traits. The use of facial expressions, especially the expression of smile, as a biometric has not been looked into great detail. However, research shows that a person can be identified from their behavioural traits including their emotional expressions. In this Chapter, we discuss a novel computational biometric model which can be derived from the smile expression. We discuss how the temporal components of a smile can be utilised to show that similarities in the smile exist for an individual and it can be enabled to create a tool which can be utilised as a biometric.

Ordinal coefficient alpha is a newly derived non-parametric reliability estimate. As with any point estimate, ordinal coefficient alpha is merely an estimate of a population parameter and tends to vary from sample to sample. Researchers report the confidence interval to provide readers with the amount of precision obtained. Several methods with differing computational approaches exist for confidence interval estimation for alpha, including the Fisher, Feldt, Bonner, and Hakstian and Whalen (HW) techniques. Overall, coverage rates for the various methods were unacceptably low with the Fisher method as the highest performer at 62%. Because of the poor performance across all four confidence interval methods, a need exists to develop a method which works well for ordinal coefficient alpha.

This research examined the performance of three parametric methods for confidence intervals: the classical, the Bonferroni, and the bootstrap-t method, as applied to estimating the mean of voucher populations in accounting. Usually auditing populations do not follow standard models. The population for accounting audits generally is a nonstandard mixture distribution in which the audit data set contains a large number of zero values and a comparatively small number of nonzero errors. This study assumed a situation in which only overstatement errors exist. The nonzero errors were assumed to be normally, exponentially, and uniformly distributed. Five indicators of performance were used. The classical method was found to be unreliable. The Bonferroni method was conservative for all population conditions. The bootstrap-t method was excellent in terms of reliability, but the lower limit of the confidence intervals produced by this method was unstable for all population conditions. The classical method provided the shortest average width of the confidence intervals among the three methods. This study provided initial evidence as to how the parametric bootstrap-t method performs when applied to the nonstandard distribution of audit populations of line items. Further research should provide a reliable confidence interval for a wider variety of accounting populations.

The aim of this study was to establish whether a relation between confidence in judgments and decisions is affected when individuals are made aware of their birth order position. Students from The University of Arizona were recruited and asked to give upper- and lower-bound ranges for a guess before and after a subtle birth order reminder. Participants also completed The General Decision Making Style questionnaire to determine whether any style correlated with birth order position. It was discovered that no statistically significant relationship was found between reminder of birth order position and confidence in decisions made. The General Decision Making Style Questionnaire indicated a significant relationship between age and the intuitive style.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / In many signal processing and telemetry applications only a portion of the Discrete Fourier Transform (DFT) of a data sequence is of interest. This paper develops an algorithm which enables computation of the FFT only over the frequency values of interest, reducing the computational complexity. As will be shown, the algorithm is also very modular which lends to efficient parallel processing implementation. This paper will begin by developing the frequency selective FFT algorithm, and conclude with a comparative analysis of the computational complexity of the algorithm with respect to the traditional FFT.

The present experiment studied the relationship between interresponse intervals and behavioral variability. Subjects emitted sequences of 4 keypresses on two keys on a variability schedule that delivered points when the current 4-response sequence differed from the previous 5 sequences. Three experimental conditions were studied; no interresponse interval, 4-s interresponse interval and 8-s interresponse interval. Interresponse intervals followed each of the first three responses in each sequence. Two groups were used to study initial training histories. Group 1 was first exposed to the no-interresponse interval condition. Group 2 was first exposed to the 4-s interresponse interval condition. Subjects were then exposed to the different interresponse interval conditions. There was little change in variability across conditions. However, the variability observed in the subjects first exposed to the 4-s interresponse interval was greater than the variability observed in subjects first exposed to no-interresponse interval. There was higher-order response patterning in both groups, but it was more pronounced in the no-interresponse interval group.

Intervals of specified fluent verbal behavior of two stutterers received response-contingent positive stimulation in the form of an accumulating points system, Assessment was made o the effect of experimental manipulation on the frequency of fluent speech intervals as well as on the frequency of subject-identified stuttering behaviors observed during the experimental session. The results indicated significant change in fluent interval frequency in the spontaneous speech of one subject. Effect of the experimental contingency was not demonstrated in the oral reading of a second subject. Stuttering. behavior data indicated that an indirect effect of the positive stimulation can change the frequency of behavior not being contingently stimulated.