A weakness of functional recovery?

-Findings are often significant, but the samples are small -Eg: Banerjee found that recovery from stroke using stem cells led to total recovery compared to just 4% of normal recovery -However, study drew conclusions based on just 5 ppts and no control group. Typical of functional recovery research as ppts are hard to recruit for research -Reseach lack validity, but waiting for larger samples may prevent the development of valuable treatments.