You might have noticed some sodas that are advertised as having 50 percent less sugar in them. Or some foods that apparently have 17 percent less fat. Or some dishwashing liquid that foams 30 percent more and can thus clean more dishes. And while there’s nothing wrong with cutting your sugar and fat intake or using a dishwashing liquid that offers great value for your money, if you were to use the products that advertise this way you would never really know whether you’re making better choices for your diet and cleanliness or not.
Why? Because of the incomplete comparisons, of course.
The very basic rule of creating comparative sentences is that you need to have at least two elements that you’ll compare in the sentence. Here’s an example:
Jenny’s bike is faster than Mike’s bike.
“Jenny’s bike” and “Mike’s bike” are the two elements that are necessary for a comparison. There’s a comparative adjective, “faster,” and a function word, “than,” between them. This is a complete comparison, and you can understand what is being compared (the bikes), which criterion is being used for the comparison (speed), and which one is the winner (Jenny’s bike).
With incomplete comparisons, we lose a crucial piece of the puzzle that gives meaning to the sentence. Let’s have a look at two examples of incomplete comparisons:
Jenny’s bike is faster than Mike’s.
Jenny’s bike is faster.
In both cases, we can’t be sure what it is that Jenny’s bike is faster than. In the first sentence, it could be Mike’s bike, but it could also be his unicycle, or his car, or even his couch. Context doesn’t always make it clear. In the second sentence, we’ve removed Mike completely, and we just know that Jenny’s bike is faster than something. That’s not a comparison, and neither is saying that something has 50 percent less fat or sugar in it.
Luckily, incomplete comparisons are easy to fix. You just need to make sure that the comparative sentence is symmetrical, so to speak. If you have Jenny’s bike on one side of the comparative adjective, you should also have a bike (or unicycle, or car, or whatever you’re comparing) on the other side of it. You can have more than one bike, though, and you can say that Jenny’s bike is faster than Mike’s and Paul’s bikes. You can even say that Jenny’s bike is faster than Mike’s bike, but not as fast as Paul’s bike. As long as you remember that comparisons need at least two elements to work, you’ll stay on the safe side.
And as for the advertising-speak that contains 50 percent less information than needed to create a comparative sentence—just skip to the nutrition labels. Unless it’s the dishwasher liquid, that is.
from Grammarly Blog http://www.grammarly.com/blog/2016/how-to-fix-incomplete-comparisons/