When students learn writing, they often are taught that if you have to say the same kind of thing more than once, word things in a slightly different way each time. The idea is to add interest through variety.
But when I work with psychology students on their writing, I often have to work hard to break them of that habit. In scientific writing, precision and clarity are the most important. This doesn’t mean that scientific writing cannot also be elegant and interesting (the vary-the-wording strategy is often just a cheap trick anyhow). But your first priority is to make sure that your reader knows exactly what you mean.
Problems arise when journalists trained in vary-the-wording write about statistics. Small thing, but take this sentence from a Slate piece (in the oft-enlightening Explainer column) about the Fort Hood shooting:
Studies have shown that the suicide rate among male doctors is 40 percent higher than among men overall and that female doctors take their own lives at 130 percent the rate of women in general.
The same comparison is being made for men and for women: how does the suicide rate among doctors compare to the general population? But the numbers are not presented in parallel. For men, the number presented is 40, as in “40 percent higher than” men in general. For women, the number is 130, as in “130 percent the rate of” women in general.
The prepositions are the tipoff that the writer is doing different things, and a careful reader can probably figure that out. But the attempt to add variety just bogs things down. A reader will have to slow down and possibly re-read once or twice to figure out that 40% and 130% are both telling us that doctors commit suicide more often than others.
Separately: why break it out by gender? In context, the writer is trying to make a point about doctors versus everybody else. Not male doctors versus female doctors. We often reflexively categorize things by gender (I’m using “we” in a society-wide sense) when it’s unnecessary and uninformative.