Fig 4. Classification tree for use of music as sleep aid.

Each node represents the predicted proportion of participants using music as a sleep aid. Participants with low Gold MSI engagement scores (equal to or less than 22) fall in node 2, with a predicted 30% of participants of using music as a sleep aid. Participants with high Gold MSI engagement scores (> 22) are further split on age between nodes 4 and 5. Participants 27 years old and younger are more likely to use music (node 4, predicted proportion 75%) and those older than 27 are somewhat more likely to use music (node 5, predicted proportion 60%).