For both research proposals and papers, authors must show awareness of critical issues already raised in previous research, or potential problem areas in their research design. This “critical analysis” can take place at any stage of the paper, be it in the methods section or in the projected outcomes section. Below you will find several expressions showing limitations of a particular area of your paper.
In this investigation there are several sources for error.
Another major source of uncertainty lies in our calculations.
It was not possible to investigate the significance of X and Y further because …
Further data collection is required to determine exactly how X affects Y.
This approach fails to take X into account.
Perhaps the most serious disadvantage of this method is…
Nevertheless, the strategy has been subjected to criticism from leading academics.
One major drawback of this approach is that …
However, this method of analysis has a number of limitations.