1、Highlight inadequacies of previous studies
The research to date has tended to focus on X rather than Y.
Most empirical studies of X have relied upon
However, these studies used non-validated methods to measure ...
2、Introduce problems and limitations with a theory
The key problem with this explanation is that ...
However, this theory does not fully explain why
One criticism of much of the literature on X is that ...
3、Criticise the method or relevant practice
A criticism of this experimental design is that
... is another potential concern because ...
Perhaps the most serious disadvantage of this method is that ..
4、Evaluate work positively
Overall, X's study is a powerful explanation of …
Smith's research is valuable for understanding of