There is widespread concern about the shortage of secondary school teachers in many developed countries. More than half of the countries in Europe and almost all school districts in the US reported challenges in recruiting and retaining teachers in some regions and for some subjects. Shortages and oversupply can coexist because of uneven distribution of teachers across subjects and geographical areas. For example, in Germany and England there is an oversupply in some subjects on the one hand and a shortage in others (European Commission/EACEA/Eurydice 2018). In Greece, there is a shortage in some remote and small islands while there is a general oversupply in the country. Teacher shortages related to remoteness of some parts of the country are mentioned in half of the countries that participated in the European Commission survey. In other cases it was the high cost of living and the large proportion of disadvantaged pupils in some large urban cities (e.g. Brussels and London) that make it difficult to attract and retain teachers.

To tackle these challenges, many education systems have offered incentives and implemented a range of programmes to attract potential teachers and retain existing teachers to difficult-to-staff areas and to some high demand subjects. The most common strategy is the offer of monetary incentives. This is because the relatively low teacher salaries are widely believed to be a deterrent to becoming and remaining a teacher. However, few robust evaluations of such financial incentives have been conducted. In fact, in England the government acknowledged that despite the large investments in these initiatives  it has been unable to address the issue (House of Commons 2017).  In the US, policy analysts have confirmed the lack of research on successful approaches to recruitment and retention for hard-to-reach areas and have called for an urgent need for a systematic review into this area (Hammer et al. 2005). Although there have been a few individual evaluatons of some of these strategies, there is no synthesis of research findings.

A large body of research already exists that looks at effective strategies to recruit and retain teachers. Unfortunately, these are predominantly based on interviews and surveys of teachers or headteachers asking them about their experiences and what they thought were effective strategies (Pesek 1993; Hammer et al. 2005; Harmon 2001). Therefore, the current evidence of the most effective approaches is still unclear.

This paper synthesises the best evidence from international empirical research to identify the most promising approaches in attracting and retaining teachers in hard-to-staff schools and areas. As far as we know, there have been no large-scale comprehensive “single-study” reviews of evidence on teacher recruitment and retention policies with a view to addressing the continual problems in teacher supply. This would involve experiments with counterfactuals to control for confounding variables. The only review (Guarino et al. 2004) that claimed to critically evaluate quality, included mainly correlational and observational studies based on administrative and sometimes longitudinal datasets that demonstrated the association between increased teacher salaries and teacher retention rates. Such studies cannot demonstrate causation. None of the studies included in the review had counterfactuals and none were randomized controlled trials. Previous reviews have tended to be a simple review of literature taking no account of the quality or validity of the evidence (e.g. Osterholm et al. 2006; Wheeler & Glennie 2007; Berry 2004, 2007; Ingersoll & Kralik 2004).

The objective of this review is to identify strategies that have the best evidence in improving teacher supply and retention in hard-to-reach areas. The reseearch question is therefore:

What are the most promising approaches to recruiting and retaining teachers in high need areas?

This is a systematic review synthesising existing empirical evidence on strategies used to recruit and retain teachers in hard-to-staff areas. The review involved a search of 13 educational, psychological and sociological electronic databases, Google and Google Scholar. These were supplemented by studies known to us and snow-balling of relevant studies cited in the retrieved studies and from reviews of literature. The key words included any causal term (or a synonym) or any research design that would be appropriate for testing a causal model, such as experiment, quasi-experiment, regression discontinuity and difference-in-difference. To avoid publication bias, the review included any material published or unpublished that mentioned these key words. A total of 6,690 research reports were identified and exported to EndNote (a reference manager) for screening. An additional 18 were found through links to known reports and hand searches. Each identified study was then screened for relevance by title and abstract first applying pre-determined inclusion and exclusion criteria. This removed 6,161 studies, retaining 547. After reading the full paper, only 52 were retained that were deemed to be relevant to the research question and specific to staffing in hard-to-staff schools and subjects. Key information about research design, data quality and measurements used were extracted. A further 27 were excluded when it was found that they were not evaluations but surveys of headteachers opinions of the most effective strategies. The remaining 25 studies were quality assessed for validity or trustworthiness of the findings using a pre-set quality appraisal tool (Gorard et al. 2017). Each study was assigned a rating ranging from 4* to 0. Four-star studies are the most secure, meaning that the evidence is most reliable or trustworthy. The research reports are then synthesised by outcomes (retention or recruitment) and by approaches (e.g. financial incentives, mentoring and induction or professional development). The outcomes of each of the approaches (i.e. positive or negative effects) in relation to the quality of the evidence are presented. Approaches with the most highly rated studies showing positive effects are considered most promising.

The majority of studies involve the use of financial incentives to attract and retain teachers in hard-to-staff areas and subjects. This is not surprising as monetary incentive policies tend to be on a national or district level with clear implementation time-scale, and thus lend themselves to experimental or quasi-experimental evaluations. Strategies like “Grow Your Own”, hiring from local training providers and housing assistance are more localised, school-based and implemented on an ad hoc basis. They are thus more difficult to be robustly evaluated. In some studies strategies meant to raise student outcomes also had an impact on teacher quality and teacher numbers. For the purpose of this review we only extracted information relating to teacher outcomes relevant to teacher supply. Findings; The most promising strategy that has been widely and robustly evaluated involves the use of financial incentives. All the higher quality studies suggest that monetary incentives can be an effective way of attracting teachers to areas where it is currently difficult to staff and for increasing the number of high-need subject teachers. However, there is no evidence that they are effective in retaining teachers. The two high quality studies suggest that they do not have any impact on retention (Steele et al. 2010; Hough et al. 2013.). There is no evidence that mentoring and induction, use of cheap contractual teachers or fast-track training are effective. These strategies have not been robustly evaluated and so there is no evidence if they work or not, but this does not suggest that they have no impact. More robust evaluations are needed for conclusive results.

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