The following was taken from this site:
http://webs.mn.catholic.edu.au/physics/emery/accuracy.htm
a) ACCURACY: Exactness or conformity to truth.
Science texts referto accuracy in two ways:
(i) Accuracy of a result or experimental procedure can refer to the percentage difference between the experimental result and the accepted value. The stated uncertainty in an experimental result should always be greater than this percentage accuracy.
(ii) Accuracy is also associated with the inherent uncertainty in a measurement. We can express the accuracy of a measurement explicitly by stating the estimated uncertainty or implicitly by the number of significant figures given. For example, we can measure a small distance with poor accuracy using a metre rule, or with much greater accuracy using a micrometer. Accurate measurements do not ensure an experiment is valid or reliable. For example consider an experiment for finding g in which the time for a piece of paper to fall once to the floor is measured very accurately. Clearly this experiment would not be valid or reliable (unless it was carried out in vacuum).
I think accuracy is confined to first-hand investigations. See outcome H12 in your syllabus - it says
evaluates ways in which accuracy and reliability could be improved in investigations. So perhaps this "gathered data" refers not to data gathered from secondary sources, but rather data obtained from measurements made in pracs?
Assuming 'accuracy' refers to the accuracy of measurements made in a first-hand investigation... Accuracy could be improved by calibrating measuring instruments, like a thermometer for example.
I'm not sure how you can assess or improve the accuracy of secondary data though... Comparing several sources and showing they are all consistent ensures reliability, not accuracy - because even though a number of different texts state the same thing, that doesn't necessarily prove what they're saying is accurate.
Edited to add -- if you have the Jacaranda textbook, take a look at the appendixes (page 653). It has a bit of information on accuracy, validity & reliability.