It would help to have some context. If the previous sentences are written directly in the first person (using "I") then perhaps you should just leave it as it is. It sounds frank and direct, but why would you want to blur it? "I prefer to" suggests that you are distancing yourself from some other study or paper that didn't stick to facts and figures. That's implicitly criticizing that other paper. But that criticism will be there no matter how you reword it.
Here are some possibilities. You must decide if I've expressed the same meaning. You must ask yourself whether these are really improvements.
1. In projects of this kind, the interpretation should not extrapolate beyond the bounds of the actual data.
2. This study will limit itself to what can be directly deduced from the quantitative data.
3. The authors of the present study prefer to confine themselves to presenting objective and quantitative data.