He's precise but inaccurate. The degree of accuracy and precision results from the combined effect of measuring equipment, technique, environmental conditions and the characteristics of the item being tested. The curve shape depends upon each individual's performance and the amount of data analyzed, but we've assumed normal or Gaussian distribution . Sometimes resolution is mistaken to be the same as accuracy. This misconception often relates to instruments with digital read-outs where a similar assumption is that, for example, a frequency counter with 11 digits must be 100 times more accurate than one with 9 digit resolution.
Resolution is just the discrimination that the instrument can show.
However, our ability to visually subdivide between the marked graduations contributes to the uncertainty of the measurement. From inspection the evidence is that the line is between 2.6 and 2.8cm and, considering only the resolution, it would be reported as 2.6 0.2cm. If some form of magnification were available, the measured value might be stated as 2.65 0.05cm. So there is an association between these two terms. Stability is sometimes also interchanged with drift and, in relation to quartz oscillator specification, the specialized term ageing rate .