This is an important limitation because of the high risk of selection bias in non-experimental evaluations of micro-finance interventions and the broad inclusion criteria adopted for studies assessing effectiveness.
This article introduces the concept of microfinance and MFIs to the academic finance community through a review of over 350 articles.
The authors included experimental, nonexperimental and case-control studies assessing the impact of microcredit or microsavings programmes on poor people in sub-Saharan Africa.
They assessed the quality of the results and excluded low-quality studies.
The lit review provides readers with a background for understanding current knowledge on a topic and illuminates the significance for the new study.
Literature review identifies problems in a study, which can be solved by collection of data.
However, the review has some important limitations.
Authors include quality assessment of included studies, but the reporting is not sufficiently transparent in terms of assessing risk of bias.
It's a review of the relevant "literature" (books, magazines, Web sites) discussing the topic you want to investigate.
The long answer is that the Review of Literature discusses techniques and equipment that are appropriate for investigating your topic.