The theoretical foundations of qualitative and quantitative methods
A disadvantage to using both qualitative and quantitative methods in a nursing study is that it may require significantly more time and resources than using one type alone. Using both types of methods requires an additional set up for data collection, analysis, interpretation, as well as writing up the findings. This may involve gathering interviews or focus groups with nurses or obtaining physician records or surveys from nurses about various topics related to patient care.
In addition, there is also potential for bias if each method is used independently without consideration for how the other approach might contribute to the overall picture being developed from the research project. For example, if only quantitative data were collected through surveys but no interviews were conducted with patients or nurses then important information may be overlooked which could affect conclusions drawn from the data collected.
Overall though, when properly planned out and implemented I believe that combining qualitative and quantitative methods in a nursing study can produce powerful results that inform practice development initiatives or guide policy decisions related to patient care quality assurance amongst many other potential outcomes.