Which concept involves making an initial assumption before testing?

The concept that involves making an initial assumption before testing is a hypothesis. A hypothesis is a proposed explanation or prediction that can be tested through experimentation or observation. It serves as a starting point for further investigation, where scientists formulate specific questions based on observations, and then create a testable statement about what they expect to happen in their experiment.

This formulation allows researchers to design experiments to support or refute the hypothesis, contributing to the scientific method's iterative nature. The emphasis on making an assumption that can be empirically tested distinguishes hypotheses from theories, which are broader explanations supported by a significant body of evidence, as well as from observations and conclusions, which arise from the data collected and analyzed during experimentation.