What is the starting assumption in scientific inquiry, often formalized as the null hypothesis?

• A. Null hypothesis
• B. Hardy-Weinberg equilibrium
• C. Punctuated equilibrium
• D. Macroevolution

Answer: (A)

The starting assumption in scientific inquiry is that there is no effect or difference—this is the null hypothesis. In practice, you set up a statement that represents “no change” or “no association” (for example, a new drug has no effect on blood pressure, or two groups have the same average outcome). This default position provides a clear baseline to test against. Through data collection and statistical analysis, you evaluate whether the evidence is strong enough to reject this neutral stance in favor of an alternative that proposes a real effect or difference. Importantly, statistics don’t prove the null; they either fail to reject it or reject it in favor of the alternative.

Other terms listed refer to specific ideas in biology, not the general starting point for inquiry. Hardy-Weinberg equilibrium describes expected allele frequencies in a population under no evolutionary forces; punctuated equilibrium is a pattern of evolutionary change characterized by long periods of little change punctuated by brief bursts of change; macroevolution refers to major evolutionary changes that occur above the species level. These are distinct concepts, whereas the null hypothesis is the foundational default assumption used to test scientific questions.