The hidden meaning of pronouns in your writing

From close to the end ...

   ... we can predict people’s college performance
   reasonably well by simply analyzing their college
   admissions essays. Across four years, we analyzed
   the admissions essays of 25,000 students and then
   tracked their grade point averages (GPAs). Higher
   GPAs were associated with admission essays that
   used high rates of nouns and low rates of verbs and
   pronouns. The effects were surprisingly strong and
   lasted across all years of college, no matter what
   the students' major.