Comparison

An act or instance of comparing,

the act or process of examining two or more objects, events, people, etc., in order to find the similarities and differences between them;

Also: a statement of the similarities and differences of two or more objects, events, people, etc.

Comparative statements may fail for various reasons such as:

• vagueness resulting when a claim involving a comparison fails to specify the thing to which the subject of the claim is being compared;
• important information concerned with the comparison made is missing, for example, it is stated that only 10% of some particular act involves a particular sub-group in the population and that this sub-group is therefore less likely to act in this way, but omitting what percentage of the population is in that sub-group 
• it is not clarified or verified that the same standard is being used, for example, a statement is made about an inferred ‘staggering’ increase in the number of prescriptions written or issued for a medication, yet it is not at all clear that the (many years’) earlier statistics used for the comparison treated the item of interest in the same way as applies with current figures;
• improper or inappropriate comparisons – so-called apples and oranges – statistics are cited to the effect that flying is much safer than driving, but a comparison which would be rather more pertinent and telling concerns the fatality rate of passengers in commercial airline flights with that of passengers in roadworthy-certified vehicles driven by highly-competent professional drivers (despite this improved selection of information it may be that taking a commercial airline flight still far outstrips road travel in safety terms, but it is very likely that the oft-stated ‘huge’ gap would narrow considerably!);
• playing fast and loose with (or simply misunderstanding) figures: for example, it is said that the average rainfall is close to identical for two geographical areas with the implication that both places are pretty-much the same when it comes to rainfall, yet there are about twice as many rainy days in one place as the other – we should be wary not to develop conclusions which are simply too strong for the evidence we possess;

Examine something to see what differences and similarities it has with one or more other things, estimate the similarity and dissimilarity of and assess the relation between two or more things.

Comparative

As compared with others;

relating to, or using as a method of comparison.

Comparable

Able to be compared;

Being of the same or equivalent kind.

Comparative judgement

Any judgement about a stimulus made relative to – in comparison with – some other stimulus.