1. You have all of the necessary information for making a decision. This information may already be available elsewhere, and you can get hold of it without running your own project. Ask your colleagues. Implement the 'Sharing is caring' approach of knowledge.
2. You are unable to define clear research objectives. Any research must start with clear goals. 'Nice to have' or 'just in case' are not defined as good enough reasons for conducting research. More clarity is required to benefit from research.
3. Research results will not influence decision making. Likely to be an operational problem related to the management style of the company. Or you could have external factors influencing decisions in a particular situation, therefore, making research findings secondary.
4. By the time research is completed, the obtained information will no longer be relevant. Any research project requires some time to prepare, field and analyse. If the research findings do not come in time for making a decision, do not conduct the project.
5. The expenditure involved in the research project will outweigh the benefits. How much could you lose (not make) if you make a wrong decision without this research?