If you follow the Cochrane Collaboration guidelines (i.e., Cochrane Handbook for Systematic Reviews of Interventions) for conducting a systematic review, which always precedes a meta-analysis, you need a minimum of two persons for many of the review steps (e.g., study selection, data extraction).

Thanks

Depende de la rigurosidad con la que quieras realizar la revisión sistemática, dos o tres personas mínimo. Cada autor debe revisar independientemente la literatura, seleccionar los artículos y los datos a utilizar, chequear los sesgos. Esto debe realizarse a ciego de los demás autores, finalmente todos los resultados de los autores deben coincidir y/o llegar a consenso. Luego, se puede proceder al análisis meta.

Gracias Carlos

I agree with Dr Warren. You need a minimum of TWO authors or you cannt complete various steps.

You need 2 or more people to do each step of a systematic review like study selection or data extraction independently and then compare the results. Then any discrepancies can be discussed. This helps to reduce data extraction errors (for empirical evidence to support this statement see for example http://www.ncbi.nlm.nih.gov/pubmed/16765272). This is true even for experienced reviewers (http://www.ncbi.nlm.nih.gov/pubmed/19683413). That said, many students are forced to do projects on their own and are not allowed to have others help. This does not mean your review is invalid if you do everything carefully (but you may have trouble later getting it published).

My systematic review  "Interventions for Alopecia areata" we are six .

See http://handbook.cochrane.org/

The answers given here are correct. Any form of research primary or 'secondary' which would include a systematic review +/- a meta-analysis ( BTW not all SR will include a M-A) is better conducted by more than one researcher.. so the correct answer is more than 2 .......for the reasons indicated above

I agree. Preferably, there should be more than two reviewers. Remember data extraction and scoring of study methodologic quality (where necessary) should always be done by two reviewers independently, and where discrepancies arise, a third author or reviewer can arbitrate it.

I agree completely with Gordon , Amanda and Zbys !

Although in theory, one seems like they might do it alone, that defeats the purpose and it is pragmatically impossible to follow the standards set by Cochrane and others without at least one other person . Sam's suggestion of a third arbitrator for discordance resolution is always a well planned process.

Good luck and enjoy the SR process and if you opt to do so, the MA (more statistical thought , but worth learning from statistical experts). COLLABORATION is KEY !

Best

Based on Cochrane Collaboration guidelines, for systematic reviews and/or meta-analysis research design the minimum number of researchers should be two.

systematic search, Data collection and data extraction ..etc should be done independently by two authors. Ideally, there should be a third author to consult in case of disagreement. So at least three authors.