Here's a suggestion:

There may be a bias in this study from the start. The study specifically seeks out a trait that the investigators assume is negative, as indicated by the use of the word 'narcissism'. Perhaps another group of researchers investigating the level of 'self-esteem' might reach a very different conclusion.

The conclusions may be prejudiced by the philosophy and frame of reference of the research team.

"Time is what prevents everything from happening at once" - John Wheeler