The past, present and future of observational research in marketing

Purpose - To introduce the contents of the special issue, and provide an integrative overview of the development of observational methodologies in marketing research, as well as some directions for the future. Design/methodology/approach - A historical review of the development of observational methods, beginning with philosophical foundations, is provided. Key philosophical debates are summarized, and trends in observational methods are described and analyzed, with particular reference to the impact of technology. Following this, the contributions to the special issue are summarized and brought together. Findings - Observational research in marketing is more than the well-known method of "participant-observation." In fact, technology has the potential to revolutionize observational research, and move it beyond a solely "qualitative" method. The internet, video, scanner-tracking, and neuroimaging methods are all likely to have a big impact on the development of traditional and innovative observation methods in the future. The articles in the special issue provide a good overview of these developments. Research limitations/implications - The views of the authors may differ from those of others. Practical implications - Observation is a far more wide-ranging strategy than many perceive. There is a need for more expertise in all types of observational methodologies within marketing research schools and departments, in order to take account of the vast opportunities which are currently emerging. Originality/value - Provides an original perspective on observational methods, and serves as a useful overview of trends and developments in the field.

The use of correlation and regression methods in optometry

Correlation and regression are two of the statistical procedures most widely used by optometrists. However, these tests are often misused or interpreted incorrectly, leading to erroneous conclusions from clinical experiments. This review examines the major statistical tests concerned with correlation and regression that are most likely to arise in clinical investigations in optometry. First, the use, interpretation and limitations of Pearson's product moment correlation coefficient are described. Second, the least squares method of fitting a linear regression to data and for testing how well a regression line fits the data are described. Third, the problems of using linear regression methods in observational studies, if there are errors associated in measuring the independent variable and for predicting a new value of Y for a given X, are discussed. Finally, methods for testing whether a non-linear relationship provides a better fit to the data and for comparing two or more regression lines are considered.

Data analysis methods in optometry. Part 5: correlation

1. Pearson's correlation coefficient only tests whether the data fit a linear model. With large numbers of observations, quite small values of r become significant and the X variable may only account for a minute proportion of the variance in Y. Hence, the value of r squared should always be calculated and included in a discussion of the significance of r. 2. The use of r assumes that a bivariate normal distribution is present and this assumption should be examined prior to the study. If Pearson's r is not appropriate, then a non-parametric correlation coefficient such as Spearman's rs may be used. 3. A significant correlation should not be interpreted as indicating causation especially in observational studies in which there is a high probability that the two variables are correlated because of their mutual correlations with other variables. 4. In studies of measurement error, there are problems in using r as a test of reliability and the ‘intra-class correlation coefficient’ should be used as an alternative. A correlation test provides only limited information as to the relationship between two variables. Fitting a regression line to the data using the method known as ‘least square’ provides much more information and the methods of regression and their application in optometry will be discussed in the next article.

Introducing consultant outpatient clinics to community settings to improve access to paediatrics:an observational impact study

Objectives - In line with a national policy to move care ‘closer to home’, a specialist children's hospital in the National Health Service in England introduced consultant-led ‘satellite’ clinics to two community settings for general paediatric outpatient services. Objectives were to reduce non-attendance at appointments by providing care in more accessible locations and to create new physical clinic capacity. This study evaluated these satellite clinics to inform further development and identify lessons for stakeholders. Methods - Impact of the satellite clinics was assessed by comparing community versus hospital-based clinics across the following measures: (1) non-attendance rates and associated factors (including patient characteristics and travel distance) using a logistic regression model; (2) percentage of appointments booked within local catchment area; (3) contribution to total clinic capacity; (4) time allocated to clinics and appointments; and (5) clinic efficiency, defined as the ratio of income to staff-related costs. Results - Satellite clinics did not increase attendance beyond their contribution to shorter travel distance, which was associated with higher attendance. Children living in the most-deprived areas were 1.8 times more likely to miss appointments compared with those from least-deprived areas. The satellite clinics’ contribution to activity in catchment areas and to total capacity was small. However, one of the two satellite clinics was efficient compared with most hospital-based clinics. Conclusions - Outpatient clinics were relocated in pragmatically chosen community settings using a ‘drag and drop’ service model. Such clinics have potential to improve access to specialist paediatric healthcare, but do not provide a panacea. Work is required to improve attendance as part of wider efforts to support vulnerable families. Satellite clinics highlight how improved management could contribute to better use of existing capacity.

An artificial neural network stratifies the risks of reintervention and mortality after endovascular aneurysm repair:a retrospective observational study

Background Lifelong surveillance after endovascular repair (EVAR) of abdominal aortic aneurysms (AAA) is considered mandatory to detect potentially life-threatening endograft complications. A minority of patients require reintervention but cannot be predictively identified by existing methods. This study aimed to improve the prediction of endograft complications and mortality, through the application of machine-learning techniques. Methods Patients undergoing EVAR at 2 centres were studied from 2004-2010. Pre-operative aneurysm morphology was quantified and endograft complications were recorded up to 5 years following surgery. An artificial neural networks (ANN) approach was used to predict whether patients would be at low- or high-risk of endograft complications (aortic/limb) or mortality. Centre 1 data were used for training and centre 2 data for validation. ANN performance was assessed by Kaplan-Meier analysis to compare the incidence of aortic complications, limb complications, and mortality; in patients predicted to be low-risk, versus those predicted to be high-risk. Results 761 patients aged 75 +/- 7 years underwent EVAR. Mean follow-up was 36+/- 20 months. An ANN was created from morphological features including angulation/length/areas/diameters/ volume/tortuosity of the aneurysm neck/sac/iliac segments. ANN models predicted endograft complications and mortality with excellent discrimination between a low-risk and high-risk group. In external validation, the 5-year rates of freedom from aortic complications, limb complications and mortality were 95.9% vs 67.9%; 99.3% vs 92.0%; and 87.9% vs 79.3% respectively (p0.001) Conclusion This study presents ANN models that stratify the 5-year risk of endograft complications or mortality using routinely available pre-operative data.

Methotrexate polyglutamates as a potential marker of adherence to long-term therapy in children with juvenile idiopathic arthritis and juvenile dermatomyositis:an observational, cross-sectional study

Introduction: Methotrexate (MTX) is a cornerstone of treatment in a wide variety of inflammatory conditions, including juvenile idiopathic arthritis (JIA) and juvenile dermatomyositis (JDM). However, owing to its narrow therapeutic index and the considerable interpatient variability in clinical response, monitoring of adherence to MTX is important. The present study demonstrates the feasibility of using methotrexate polyglutamates (MTXPGs) as a biomarker to measure adherence to MTX treatment in children with JIA and JDM. Methods: Data were collected prospectively from a cohort of 48 children (median age 11.5 years) who received oral or subcutaneous (SC) MTX therapy for JIA or JDM. Dried blood spot samples were obtained from children by finger pick at the clinic or via self- or parent-led sampling at home, and they were analysed to determine the variability in MTXPG concentrations and assess adherence to MTX therapy. Results: Wide fluctuations in MTXPG total concentrations (>2.0-fold variations) were found in 17 patients receiving stable weekly doses of MTX, which is indicative of nonadherence or partial adherence to MTX therapy. Age (P = 0.026) and route of administration (P = 0.005) were the most important predictors of nonadherence to MTX treatment. In addition, the study showed that MTX dose and route of administration were significantly associated with variations in the distribution of MTXPG subtypes. Higher doses and SC administration of MTX produced higher levels of total MTXPGs and selective accumulation of longer-chain MTXPGs (P < 0.001 and P < 0.0001, respectively). Conclusions: Nonadherence to MTX therapy is a significant problem in children with JIA and JDM. The present study suggests that patients with inadequate adherence and/or intolerance to oral MTX may benefit from SC administration of the drug. The clinical utility of MTXPG levels to monitor and optimise adherence to MTX in children has been demonstrated. Trial registration: ISRCTN Registry identifier: ISRCTN93945409. Registered 2 December 2011.

Clinical significance of medication reconciliation in children admitted to a UK pediatric hospital:observational study of neurosurgical patients

Background: In December 2007, the National Institute for Health and Clinical Excellence and the National Patient Safety Agency in the UK (NICE-NPSA) published guidance that recommends all adults admitted to hospital receive medication reconciliation, usually by pharmacy staff. A costing and report tool was provided indicating a resource requirement of d12.9 million for England per year. Pediatric patients are excluded from this guidance. Objective: To determine the clinical significance of medication reconciliation in children on admission to hospital. Methods: A prospective observational study included pediatric patients admitted to a neurosurgical ward at Birmingham Childrens Hospital, Birmingham, England, between September 2006 and March 2007. Medication reconciliation was conducted by a pharmacist after the admission of each of 100 consecutive eligible patients aged 4 months to 16 years. The clinical significance of prescribing disparities between pre-admission medications and initial admission medication orders was determined by an expert multidisciplinary panel and quantified using an analog scale. The main outcome measure was the clinical signficance of unintentional variations between hospital admission medication orders and physician-prescribed pre-admission medication for repeat (continuing) medications. Results: Initial admission medication orders for children differed from prescribed pre-admission medication in 39%of cases. Half of all resulting prescribing variations in this setting had the potential to cause moderate or severe discomfort or clinical deterioration. These results mirror findings for adults. Conclusions: The introduction of medication reconciliation in children on admission to hospital has the potential to reduce discomfort or clinical deterioration by reducing unintentional changes to repeat prescribed medication. Consequently, there is no justification for the omission of children from the NICENPSA guidance concerning medication reconciliation in hospitals, and costing tools should include pediatric patients. © 2010 Adis Data Information BV. All rights reserved.