The title of my research is " contribution of agroforestry in soil fertility to small farmers." I'm using mixed-method research so I'm having difficulty creating hypotheses since I don't know which type of hypothesis should I use.
Yes, it is allowed to use a null hypothesis in mixed-method research. In fact, the combination of quantitative and qualitative methods can help researchers to more effectively evaluate the validity of their results and draw more meaningful conclusions from their data. The use of a null hypothesis in mixed-method research can provide researchers with a more comprehensive understanding of their research question and allow them to draw more accurate and valid conclusions.