More than ambiguity

More picky stuff.
A student wrote about an exercise sentence:
"Many office managers value high achievers more than risk takers.” I thought that this sentence should be left unchanged, but in the back of the book it was changed to “Many officers managers value high achievers over risk takers.” This correction was helpful for me. It made me look over the initial sentence multiple times to see what was wrong with it. Finally, I discovered the lack of clarity in the “more than” statement. Do office managers value high achievers more than risk takers value high achievers? Or do officer managers value high achievers more than they value risk takers? 

Good questions, and you can see how comparisons so often lead to ambiguity! Generally I change "over" to "more than" ("over" being a word of placement, not comparison). But in this case, you can pinpoint the problem, as "more than" makes who values and who is valued ambiguous. Another way to fix it in an edit would be to add something to "risk takers" to make its function clear-- is it a second subject (that is, doing the valuing) or an object (being valued)?
Let's see:
Risk takers as a second subject-- add a second predicate/verb (do-- that is "more than risk takers value high achievers").
Many office managers value high achievers more than risk takers do.
Or, as is more likely the meaning, risk takers are another object-- being valued.
Many office managers value high achievers more than they value risk takers.

But "they" (referring to managers) might be ambiguous itself! You can see what changing the connector word there to "over" is easier. :)
 
Alicia