Can Non-Randomised Studies of Interventions Provide Unbiased Effect Estimates? A Systematic Review of Internal Replication Studies.

Non-randomized studies of intervention effects (NRS), also called quasi-experiments, provide useful decision support about development impacts. However, the assumptions underpinning them are usually untestable, their verification resting on empirical replication. The internal replication study aims to do this by comparing results from a causal benchmark study, usually a randomized controlled trial (RCT), with those from an NRS conducted at the same time in the sampled population. We aimed to determine the credibility and generalizability of findings in internal replication studies in development economics, through a systematic review and meta-analysis. We systematically searched for internal replication studies of RCTs conducted on socioeconomic interventions in low- and middle-income countries. We critically appraised the benchmark randomized studies, using an adapted tool. We extracted and statistically synthesized empirical measures of bias. We included 600 estimates of correspondence between NRS and benchmark RCTs. All internal replication studies were found to have at least "some concerns" about bias and some had high risk of bias. We found that study designs with selection on unobservables, in particular regression discontinuity, on average produced absolute standardized bias estimates that were approximately zero, that is, equivalent to the estimates produced by RCTs. But study conduct also mattered. For example, matching using pre-tests and nearest neighbor algorithms corresponded more closely to the benchmarks. The findings from this systematic review confirm that NRS can produce unbiased estimates. Authors of internal replication studies should publish pre-analysis protocols to enhance their credibility

Quantifying the effectiveness and health co-benefits of climate change mitigation actions across sectors: a protocol for an umbrella review

Background: Effective and rapid actions are required to achieve global goals for climate change mitigation, and there is an opportunity to ensure that the actions taken are also positive for human health. However, little is known about the relative magnitude of the health co-benefits that can be achieved from mitigation actions, so robust and comprehensive syntheses of the evidence on the nature and effects of relevant actions are required. This paper presents a protocol for an interdisciplinary and cross-sectoral umbrella review of systematic reviews, synthesising modelled and empirical evidence on such actions. Methods: Nine bibliographic databases will be searched, capturing literature across a wide range of disciplines and sectors. Unique records retrieved by the searches will be screened by two independent reviewers. The quality of all the included systematic reviews will be assessed using A MeaSurement Tool to Assess Systematic Reviews (AMSTAR) 2 critical appraisal tool. Data will be extracted on methodological and thematic characteristics of the reviews, nature of the actions, and their effects on greenhouse gas emission reduction, health, and its determinants, as well as any other reported effects and interactions across different actions. Results: Narrative and quantitative synthesis methods will be used to create a typology of relevant actions, map pathways to their impacts on health, compare the magnitude of health and greenhouse gas (GHG) emission reduction impacts by selected characteristics of the actions and the nature of the evidence, as well as to identify gaps in evidence syntheses. Conclusion: This review will identify the most effective actions for global climate change mitigation and health based on the best available scientific evidence.   This protocol has been registered in PROSPERO, Reg No.: CRD42021239292.</ns4:p

PROTOCOL: The impact of agricultural mechanisation on women's economic empowerment: A mixed-methods systematic review

This is the protocol for a Campbell systematic review. The main objective of the review is to answer the following questions: What is the impact of mechanisation on agriculture? What is the impact of mechanisation on women's economic empowerment? The study will review the impact of mechanisation on labour demand and supply, land and labour productivity, farmers' incomes, health and women's empowerment. All literature will be considered, including nonintervention studies and studies not reporting gender-disaggregated results

PROTOCOL: Interventions promoting resilience through climate-smart agricultural practices for women farmers: A systematic review

This is the protocol for a Campbell systematic review. The objectives are as follows: the primary objective of this review is to synthesise evidence of the effectiveness of interventions to promote climate‐smart agriculture to enhance agricultural outcomes and resilience of women farmers in low‐and‐middle‐income countries (research question 1). The secondary objective is to examine evidence along the causal pathway from access to interventions to promote climate‐smart agriculture to empowering women so that they can use climate‐smart technology. And such outcomes include knowledge sharing, agency improvement, resource access and decision‐making (research question 2)

Effectiveness of life skills training interventions for the empowerment of women in developing countries: a systematic review

This systematic review evaluates the effectiveness of life skills training intervention programmes in empowering women in developing countries. Life skills training has emerged as a popular approach to empowerment, often as a part of a multicomponent intervention. Overall, the systematic review finds that life skills positively affect a range of self, social and economic empowerment outcomes. Small but significant positive changes were detected for a range of outcome areas including leadership, attitudes to gender issues, sexual and reproductive health and rights, employment and life skills themselves. There is some indication that multi-component approaches may be more effective. Life skills training can be called a promising approach with potential for supporting women's empowerment in climate and agricultural projects. Including life skills interventions within components of Green Climate Fund and International Fund for Agricultural Development project interventions can contribute to transforming women’s lives, livelihoods and societal roles

The Effectiveness of Contract Farming for Raising Income of Smallholder Farmers in Low- and Middle-Income Countries: a Systematic Review

Contract farming is used by an increasing number of firms as a preferred modality to source products from smallholder farmers in low and middle-income countries. Quality requirements of consumers, economies of scale in production or land ownership rights are common incentives for firms to offer contractual arrangements to farmers. Prices and access to key technology, key inputs or support services are the main incentives for farmers to enter into these contracts. There is great heterogeneity in contract farming, with differences in contracts, farmers, products, buyers, and institutional environments. The last decade shows a rapid increase in studies that use quasi-experimental research designs to assess the effects of specific empirical instances of contract farming on smallholders. The objective of this systematic review was to distill generalised inferences from this rapidly growing body of evidence. The review synthesised the studies in order to answer two questions: 1: What is known about the effect size of contract farming on income and food security of smallholder farmers in low- and middle-income countries? 2: Under which enabling or limiting conditions are contract farming arrangements effective for improving income and food security of smallholders

Analysis of shared heritability in common disorders of the brain

ience, this issue p. eaap8757 Structured Abstract INTRODUCTION Brain disorders may exhibit shared symptoms and substantial epidemiological comorbidity, inciting debate about their etiologic overlap. However, detailed study of phenotypes with different ages of onset, severity, and presentation poses a considerable challenge. Recently developed heritability methods allow us to accurately measure correlation of genome-wide common variant risk between two phenotypes from pools of different individuals and assess how connected they, or at least their genetic risks, are on the genomic level. We used genome-wide association data for 265,218 patients and 784,643 control participants, as well as 17 phenotypes from a total of 1,191,588 individuals, to quantify the degree of overlap for genetic risk factors of 25 common brain disorders. RATIONALE Over the past century, the classification of brain disorders has evolved to reflect the medical and scientific communities' assessments of the presumed root causes of clinical phenomena such as behavioral change, loss of motor function, or alterations of consciousness. Directly observable phenomena (such as the presence of emboli, protein tangles, or unusual electrical activity patterns) generally define and separate neurological disorders from psychiatric disorders. Understanding the genetic underpinnings and categorical distinctions for brain disorders and related phenotypes may inform the search for their biological mechanisms. RESULTS Common variant risk for psychiatric disorders was shown to correlate significantly, especially among attention deficit hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder (MDD), and schizophrenia. By contrast, neurological disorders appear more distinct from one another and from the psychiatric disorders, except for migraine, which was significantly correlated to ADHD, MDD, and Tourette syndrome. We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine. We also identify significant genetic sharing between disorders and early life cognitive measures (e.g., years of education and college attainment) in the general population, demonstrating positive correlation with several psychiatric disorders (e.g., anorexia nervosa and bipolar disorder) and negative correlation with several neurological phenotypes (e.g., Alzheimer's disease and ischemic stroke), even though the latter are considered to result from specific processes that occur later in life. Extensive simulations were also performed to inform how statistical power, diagnostic misclassification, and phenotypic heterogeneity influence genetic correlations. CONCLUSION The high degree of genetic correlation among many of the psychiatric disorders adds further evidence that their current clinical boundaries do not reflect distinct underlying pathogenic processes, at least on the genetic level. This suggests a deeply interconnected nature for psychiatric disorders, in contrast to neurological disorders, and underscores the need to refine psychiatric diagnostics. Genetically informed analyses may provide important "scaffolding" to support such restructuring of psychiatric nosology, which likely requires incorporating many levels of information. By contrast, we find limited evidence for widespread common genetic risk sharing among neurological disorders or across neurological and psychiatric disorders. We show that both psychiatric and neurological disorders have robust correlations with cognitive and personality measures. Further study is needed to evaluate whether overlapping genetic contributions to psychiatric pathology may influence treatment choices. Ultimately, such developments may pave the way toward reduced heterogeneity and improved diagnosis and treatment of psychiatric disorders

Does citizen engagement improve development outcomes? A realist-informed systematic review of participation and accountability mechanisms

Effective, accountable and transparent institutions, that engage in inclusive and participatory governance, are crucial for the sustainability of global development investments. However, there is a debate about whether effective approaches to improving governance processes operate from the bottom up (e.g. by enabling citizens to hold service providers accountable) or the top down (by enabling service providers to be held accountable by the State). This paper systematically reviews participation and accountability mechanisms in a range of sectors, drawing on principles of realist evaluation to develop and test middle-range theory using framework synthesis and statistical meta-analysis. We show that interventions promoting citizen engagement through participatory priority setting or accountability mechanisms are often effective in stimulating active citizen engagement in service delivery and realising improvements in access to services, where they facilitate direct engagement between service users and front-line service providers, such as in health care. However, citizen engagement interventions alone are not effective where services are accessed independently of service provider staff, for example road infrastructure. Interventions promoting participation by increasing citizens’ pressures on politicians to hold providers to account are also not usually able to influence service delivery

Data for: "Impact on childhood mortality of interventions to improve drinking water, sanitation, and hygiene (WASH) to households: Systematic review and meta-analysis"

Data used for the analysis outlined in "Impact on childhood mortality of interventions to improve drinking water, sanitation, and hygiene (WASH) to households: Systematic review and meta-analysis"