Inference

In the syllabus and the exam

An inference is a reasoned explanation offered for something that has already been observed, and it appears throughout Paper 1 and Paper 2 wherever candidates are given a diagram, a set of results, or a described observation and asked what conclusion can reasonably be drawn from it. A good inference goes beyond simply restating the observation; for example, if the observation is 'the leaf turned blue-black at the tip but stayed orange-brown at the base after iodine testing', an acceptable inference is 'starch is present at the tip but absent at the base, so photosynthesis, or the transport of its products, has occurred unevenly across the leaf' rather than just repeating the colour change. Because an inference is only a plausible explanation and not a proven fact, more than one reasonable inference can sometimes be accepted from the same observation, and candidates are rewarded for logical reasoning that fits the data given. The most common confusion is between inference and observation itself: an observation is what the senses or an instrument directly detect (the colour changed), while an inference is the idea proposed to account for it (starch must be present). Inference is also frequently mixed up with prediction, which looks forward to an untested situation, whereas inference looks back at data already collected. Because inference-writing is also assessed as a standalone science process skill in Paper 1's multiple-choice items, candidates should practise distinguishing a strong inference, which explains the observation using a biological mechanism, from a weak one that merely restates the observation in different words.

Example

After observing that leaves on the shaded side of a plant are paler than those in direct sunlight, a student infers that lower light intensity reduces chlorophyll production.

Related terms

HypothesisResponding variable

Source:SRC-DSKP-EN