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PubMed2002

Income, income inequality and health: what can we learn from aggregate data?

It has been suggested that, especially in countries with high per capita income, there is an independent effect of income distribution on the health of individuals. One source of evidence in support of this relative income hypothesis is the analysis of aggregate cross-section data on population health, per capita income and income inequality. We examine the empirical robustness of cross-section analyses by using a new data set to replicate and extend the methodology in a frequently cited paper. The estimated relationship between income inequality and population health is not significant in any of our estimated models. We also argue there are serious conceptual difficulties in using aggregate cross-sections as a means of testing hypotheses about the effect of income, and its distribution, on the health of individuals.

Cross-Sectional Studies↗
PubMed2005

Confidentiality and confidence: is data aggregation a means to achieve both?

The recent adoption of electronic technologies for use in management of personal health data have been accompanied by a commensurate level of concern about privacy. Public health authorities have been able to continue their full access to personal information, while restricting the information given to academic health researchers through the practice of aggregation. Through this band-aid strategy, there is a very real potential that critical pieces of information are missing for the purposes of research. While this might be a logical sacrifice in order to preserve individual privacy, quantitative analysis of the privacy gained through this method of aggregation shows that little, if any, benefit is achieved. If aggregation were the sole available means to reach the aims of both privacy and research, then further analysis of the practice of aggregation would be unnecessary. Yet suitable privacy protection techniques abound, enabling academic research to progress while adding true protection to individual health information.

Adult↗
PubMed1992

Psychometric examination of instruments using aggregated data.

The techniques used to examine the psychometric properties of instruments that measure concepts where individual responses are aggregated to form an index describing a group level phenomenon are reviewed. This examination includes assessing the content validity of items to determine how well they measure group level concepts as well as analyzing reliability and validity at the aggregated rather than individual level. Additional techniques to test for within and between group variability are presented. The latter approaches are useful in determining the consistency and adequacy of individual responses at the group level.

Group Processes↗
PubMed1992

Aggregating data from multiple informants in child psychiatry epidemiological research.

One of the issues confronting the field of child psychiatric epidemiology is devising ways to aggregate discrepant reports from multiple informants obtained in structured diagnostic assessments of children and adolescents. The present report uses data from an epidemiological community survey to attempt to address this issue. The results obtained through statistical procedures designed to identify the "optimal" informant for specific symptomatic criteria and diagnoses do not seem to offer a clear-cut advantage over a simple combinatorial rule that identifies symptomatic criteria as positive when they are acknowledged as positive by either parent or child informants.

Adolescent↗
PubMed1996

Spatial data aggregation: exploratory analysis of road accidents.

This paper is limited to the "size problem": it empirically and systematically examines to what extent the length of road segment influences the statistical description of accident counts and density. Univariate descriptive statistics are systematically measured for accident count and ratio, using different motorway segment lengths. A classification of the studied aggregation levels is proposed leading to three distinct groups of segments: (1) very small segments (1 hm), where observed accident counts are almost Poisson distributed, (2) large segments (more than 20 hm), where accident counts are almost normally distributed, and (3) medium size segments (3-20 hm), where accident counts have an intermediate empirical distribution. It is suggested that generalizations made at one level of spatial aggregation may not necessarily hold at another level. Conclusions derived at one scale may be invalid at another. The paper shows how important preliminary examination of the data can be, without any sophisticated statistical test. It also shows that one best or unique level of aggregation is not available: it depends upon the objective of the study. Results of any statistical analysis or modelling procedure should be seen as conditional on the scale of the analysis.

Accidents, Traffic↗
PubMed2002

Indiscriminate data aggregations in meta-analysis. A cause for concern among policy makers and social scientists.

Whether you are a policy maker of social scientist, you are slowly being drowned in a sea of often inconsistent research data. Proponents of meta-analysis claim that such data can be objectively and usefully summarized for you. The author notes how the assumptions of the meta-analytic model preclude the synthesis of experimental data (which has a clear cause-and-effect logic) with quasi-experimental and/or nonexperimental data (both of which lack such clarity). Yet in the author's review of 64 recent meta-analytic articles, 11 were found to improperly make such aggregations. Why? The author shows how the guidance provided by the leading proponents of meta-analysis either blurs the distinction or is misleading.

Bias↗
PubMed2004

Zone design for environment and health studies using pre-aggregated data.

Many environment and health studies employ geographical areas as the units of analysis, either through choice or necessity. The design of these areas can greatly influence any observed spatial relationships or patterns-an effect known as the modifiable areal unit problem. In this paper we identify the phenomena and processes which are typically measured in environment and health studies and present a conceptualisation for their representation as data objects in spatial analysis. We discuss the circumstances under which we find ourselves using areas for representation and outline the application of zone design techniques for the creation of such areas in environment and health studies. An empirical study of the relationship between deprivation and limiting long-term illness in the former county of Avon, UK, is employed to demonstrate the potential usefulness of zone design techniques for creating zones with stable estimates and for exploring the sensitivity of relationships to changes in the zoning system. In particular, we illustrate the inappropriateness of the 1991 Census enumeration district and ward zoning systems for such an analysis and conclude that automatically designed aggregations may be a more appropriate basis for analysis than any pre-existing zoning system.

Adolescent↗
PubMed2005

Quantitative reanalysis of aggregate data on IQ in sexual offenders.

General intelligence has been the most commonly studied neuropsychological characteristic of sexual offenders for over 70 years. Results, however, have been highly inconsistent. To assess whether sexual offenders score lower in IQ than nonsexual offenders and to explore which sexual offense characteristics relate to IQ, the authors reanalyzed all reports providing sufficient information. Data spanned 236 samples, comprising 25,146 sexual offenders and controls. The literature contained sufficient information to permit comparison of adult versus juvenile sexual offenders, offenders targeting children versus adults, offenders targeting their own versus unrelated children, and offenders targeting boys versus girls. Results confirm the association between IQ and sexual offending and suggest that previous discrepancies are attributable to how many pedophilic individuals were in each sample.

Adult↗
PubMed1988

Deriving relative risks from aggregate data. 1. Theory.

Sociological macro analyses of the association between risk factors and mortality can be seen as a valuable supplement to epidemiological micro studies. However, sociologists and epidemiologists typically employ different measures of association and this hampers strict comparisons of findings. This study presents a synthetic approach relying on both micro and macro data. In Part 1, the mathematical relations between the relative risk and the attributable fraction on the one hand, and the regression coefficient on the other are derived in order to make cross level comparisons possible. Part 2 provides an empirical illustration of the approach.

Epidemiologic Methods↗
PubMed1996

Clinical safety of 311C90: aggregated data from patients and volunteers to date.

The tolerability of 311C90, a novel, selective and highly effective 5-HT1D receptor agonist in development for the acute treatment of migraine, has been evaluated in a number of clinical pharmacology and patient studies across the dose range 1-50 mg. 311C90 has been well tolerated across the entire dose range and no clinically relevant changes in routine laboratory parameters, blood pressure or ECG recordings have been observed. Adverse experiences reported are generally dose related, mild to moderate and resolve spontaneously. Chest-related symptoms occur infrequently and the cardiovascular safety profile of 311C90 is considered particularly favourable. 311C90, therefore, possesses a desirable safety profile which is well suited to broad-based outpatient administration.

Adult↗
PubMed2006

Chemotherapy in advanced gastric cancer: a systematic review and meta-analysis based on aggregate data.

PURPOSE: This systematic review and meta-analysis were performed to assess the efficacy and tolerability of chemotherapy in patients with advanced gastric cancer. METHODS: Randomized phase II and III clinical trials on first-line chemotherapy in advanced gastric cancer were identified by electronic searches of Medline, Embase, the Cochrane Controlled Trials Register, and Cancerlit; hand searches of relevant abstract books and reference lists; and contact to experts. Meta-analysis was performed using the fixed-effect model. Overall survival, reported as hazard ratio (HR) with 95% CI, was the primary outcome measure. RESULTS: Analysis of chemotherapy versus best supportive care (HR = 0.39; 95% CI, 0.28 to 0.52) and combination versus single agent, mainly fluorouracil (FU) -based chemotherapy (HR = 0.83; 95% CI = 0.74 to 0.93) showed significant overall survival benefits in favor of chemotherapy and combination chemotherapy, respectively. In addition, comparisons of FU/cisplatin-containing regimens with versus without anthracyclines (HR = 0.77; 95% CI, 0.62 to 0.95) and FU/anthracycline-containing combinations with versus without cisplatin (HR = 0.83; 95% CI, 0.76 to 0.91) both demonstrated a significant survival benefit for the three-drug combination. Comparing irinotecan-containing versus nonirinotecan-containing combinations (mainly FU/cisplatin) resulted in a nonsignificant survival benefit in favor of the irinotecan-containing regimens (HR = 0.88; 95% CI, 0.73 to 1.06), but they have never been compared against a three-drug combination. CONCLUSION: Best survival results are achieved with three-drug regimens containing FU, an anthracycline, and cisplatin. Among these, regimens including FU as bolus exhibit a higher rate of toxic deaths than regimens using a continuous infusion of FU, such as epirubicin, cisplatin, and continuous-infusion FU.

Antineoplastic Combined Chemotherapy Protocols↗