Tahsen - in my mind this is 'false'. A well constructed mixed methods study is no more difficult to review than a single qualitative or quantitative study. True - reviewers would have to be knowledgeable and conversant with a wide range of methods and methodologies - both for qualitative and quantitative approaches - but most good quality and established journals request this type of information from reviewers so that mixed method studies can be allocated to those with the skills to review them effectively.