Avoidable Waste in Ophthalmic Epidemiology: A Review of Blindness Prevalence Surveys in Low and Middle Income Countries 2000-2014.

PURPOSE: Sources of avoidable waste in ophthalmic epidemiology include duplication of effort, and survey reports remaining unpublished, gaining publication after a long delay, or being incomplete or of poor quality. The aim of this review was to assess these sources of avoidable waste by examining blindness prevalence surveys undertaken in low and middle income countries (LMICs) between 2000 and 2014. METHODS: On December 1, 2016 we searched MEDLINE, EMBASE and Web of Science databases for cross-sectional blindness prevalence surveys undertaken in LMICs between 2000 and 2014. All surveys listed on the Rapid Assessment of Avoidable Blindness (RAAB) Repository website ("the Repository") were also considered. For each survey we assessed (1) availability of scientific publication, survey report, summary results tables and/or datasets; (2) time to publication from year of survey completion and journal attributes; (3) extent of blindness information reported; and (4) rigour when information was available from two sources (i.e. whether it matched). RESULTS: Of the 279 included surveys (from 68 countries) 186 (67%) used RAAB methodology; 146 (52%) were published in a scientific journal, 57 (20%) were published in a journal and on the Repository, and 76 (27%) were on the Repository only (8% had tables; 19% had no information available beyond registration). Datasets were available for 50 RAABs (18% of included surveys). Time to publication ranged from <1 to 11 years (mean, standard deviation 2.8 ± 1.8 years). The extent of blindness information reported within studies varied (e.g. presenting and best-corrected, unilateral and bilateral); those with both a published report and Repository tables were most complete. For surveys published and with RAAB tables available, discrepancies were found in reporting of participant numbers (14% of studies) and blindness prevalence (15%). CONCLUSION: Strategies are needed to improve the availability, consistency, and quality of information reported from blindness prevalence surveys, and hence reduce avoidable waste.

Growing Up in New Zealand cohort alignment with all New Zealand births.

OBJECTIVE: To compare the birth characteristics of the Growing Up in New Zealand cohort with those of all New Zealand (NZ) births over a similar time period, and to describe cohort alignment to current NZ births. METHOD: The Growing Up in New Zealand longitudinal study recruited 6,846 children from before birth via their pregnant mothers who were residing in the greater Auckland and Waikato regions during 2009 and 2010. Data were collected from mothers antenatally and six weeks after their expected delivery date, and from routine perinatal health records. These data were compared to Ministry of Health data for all births in NZ between 2007 and 2010. RESULTS: The proportion of males and singleton births were not statistically different to national births. Compared to national births fewer of the cohort children were born low birth weight (4.9% vs. 6.1%, p<0.0001) or preterm (6.4% vs. 7.4%, p=0.001) and the cohort was expected to be more ethnically diverse than national births. CONCLUSION: Birth parameters for the cohort were generally closely aligned to all NZ births in 2007-2010. Some statistically significant differences reflected small absolute differences, attributable in some part to cohort recruitment requiring survival to six weeks post expected delivery. IMPLICATIONS: The explicit documentation of the alignment of the cohort to national data provides assurance that the study is well placed to deliver findings that can inform policy development relevant to the diversity of the contemporary NZ child population.

Reinforcer magnitude and demand under fixed-ratio schedules with domestic hens.

This study compared three methods of normalizing demand functions to allow comparison of demand for different commodities and examined how varying reinforcer magnitudes affected these analyses. Hens responded under fixed-ratio schedules in 40-min sessions with response requirement doubling each session and with 2-s, 8-s, and 12-s access to wheat. Over the smaller fixed ratios overall response rates generally increased and were higher the shorter the magazine duration. The logarithms of the number of reinforcers obtained (consumption) and the fixed ratio (price) were well fitted by curvilinear demand functions (Hursh et al., 1988. Journal of the Experimental Analysis of Behavior 50, 419-440) that were inelastic (b negative) over small fixed-ratios. The fixed ratio with maximal response rate (Pmax) increased, and the rate of change of elasticity (a) and initial consumption (L) decreased with increased magazine duration. Normalizing consumption using measures of preference for various magazine durations (3-s vs. 3-s, 2-s vs. 8-s, and 2-s vs. 12-s), obtained using concurrent schedules, gave useful results as it removed the differences in L. Normalizing consumption and price (Hursh and Winger, 1995. Journal of the Experimental Analysis of Behavior 64, 373-384) unified the data functions as intended by that analysis. The exponential function (Hursh and Silberberg, 2008. Psychological Review, 115, 186-198) gave an essential value that increased (i.e., α decreased significantly) as magazine duration decreased. This was not as predicted, since α should be constant over variations in magazine duration, but is similar to previous findings using a similar procedure with different food qualities (hens) and food quantities (rats).

How do you recruit and retain a prebirth cohort? Lessons learnt from growing up in New Zealand.

Growing Up in New Zealand, a longitudinal study following nearly 7,000 children, has faced some unique challenges in identifying, enrolling, and retaining a large and diverse antenatal cohort. Identification of a study region with population demographics that enabled enrollment of an appropriately diverse sample was required as was intensive community and participant engagement in order to promote the study. Complementary methods used included direct engagement with prospective participants and the community and indirect engagement via media. Thus far, retention rates above 95% have been achieved by maintaining a multimethod approach that includes valuing participants and building trusting relationships, strong brand recognition, community engagement, maintenance of participant contact and location records, ensuring high-quality interactions between the participants and the study, pretesting measures and methods prior to the main cohort, and using participant feedback to inform the measures and methods used in future waves of data collection.

A concurrent-choice analysis of amount-dependent temporal discounting.

Amount-dependent temporal discounting refers to the differential rates at which the values of large and small rewards are discounted over time. A lower rate of discounting of larger rewards is known as the magnitude effect. The present study aimed to establish a magnitude effect in humans using a concurrent-choice procedure. Participants indicated their strength of preference between hypothetical outcomes that differed in monetary value, and in the delay at which they were available. Most studies of temporal discounting measure preference using indifference points estimated from a titration procedure. The present study measured preference using a concurrent choice procedure. The main analysis demonstrated temporal discounting and a magnitude effect. Further analysis showed that the result was consistent with the matching law.

The effects of session length on demand functions generated using FR schedules.

In comparing open and closed economies, researchers often arrange shorter sessions under the former condition than under the latter. Several studies indicate that session length per se can affect performance and there are some data that indicate that this variable can influence demand functions. To provide further data, the present study exposed domestic hens to series of increasing fixed-ratio schedules with the length of the open-economy sessions varied over 10, 40, 60, and 120 min. Session time affected the total-session response rates and pause lengths. The shortest session gave the greatest response rates and shortest pauses and the longest gave the lowest response rates and longest pauses. The total-session demand functions also changed with session length: The shortest session gave steeper initial slopes (i.e., the functions were more elastic at small ratios) and smaller rates of change of elasticity than the longest session. Response rates, pauses, and demand functions were, however, similar for equivalent periods of responding taken from within sessions of different overall lengths (e.g., total-session data for 10-min sessions and the data for the first 10 min of 120-min sessions). These findings suggest that differences in session length can confound the results of studies comparing open and closed economies when those economies are arranged in sessions that differ substantially in length, hence data for equivalent-length periods of responding, rather than total-session data, should be of primary interest under these conditions.