Observational learning has shown to be a successful intervention for writing. Until now, however, studies have only been performed with normal-hearing participants, usually high school or university students. Additionally, there have been conflicting results in whether subjective text quality correlates with one or more objectively measured text characteristics. In this study, we measured the effect of observational learning in a group of four university students with hearing impairment, and compared the results with those of a group of 10 students with normal hearing who did the same intervention, and those of a control group consisting of 10 students with normal hearing who did not do the intervention. Subjective text quality ratings and nine objectively measured text characteristics were collected for three argumentative texts written by each of the participants. In between writing these three texts, the participants in the experimental groups watched a video of a model writer who read out loud and corrected a similar kind of text. The statistical analysis showed significant correlations between the subjective ratings and four out of the nine objective measures, but no significant intervention effect. These findings suggest that observation-learning intervention is most effective when the model writer is a peer learner, and when the intervention is stretched out over time. Additionally, the method may be better suited for learners younger than the ones who were included in the present study.