# Creation, Analysis and Evaluation of AnnoMI, a Dataset of Expert-Annotated Counselling Dialogues +
## 6 Dataset Analysis
### Uttrance Length Distributions  
Following [13], we study the lengths (number of words) of utterances of different types. To better represent the distribution of individual utterance lengths, we opt for violin plots to render a kernel density estimation of each underlying distribution, with the first, second, and third quartiles marked as dashed lines. This applies to Figures 7-9, though Figure 9 shows the distribution of utterance length ratios instead of absolute lengths.  
Figure 7 shows the therapist and client utterance length distributions in high- and low-quality MI. It is clear that the client utterance distributions are similar in MI-adherent and non-adherent sessions, whereas therapist utterances are generally shorter in high-quality MI than in low-quality MI, which is another indicator that an MI-adherent therapist takes more time to actively listen to and understand their client.  
Figure 8: Utterance lengths (number of words) of different therapist behaviours in high- and low-quality MI.  
Figure 7: Lengths (number of words) of therapist and client utterances in high- and low-quality MI.  
Figure 9: Ratios between the length (number of words) of the next-turn therapist response (broken down into 4 types of therapist behaviours) and that of the current-turn client utterance.  
Figure 8 shows a more fine-grained therapist utterance length distribution with regard to each therapist behaviour. For Reflection, the median utterance length is roughly the same in high- and low-quality MI, but the proportion of shorter utterances is clearly larger in the former. In terms of Question, an MI-adherent therapist tends to pose slightly longer questions than their non-adherent counterpart, which may suggest that an MI-adherent therapist more often asks tailored and nuanced questions. Input is substantially longer in both high- and low-quality MI, but input from an MI-non-adherent therapist is generally 10 words or more longer than that from an adherent counsellor, indicating the relatively larger degree to which an MI-non-adherent therapist talks from their own perspective. Finally, the generally short (no more than a few words) utterances of the Other behaviour show that, similar to neutral talk, these utterances mostly carry little meaning and are often simply used to facilitate the conversation.  
We also investigate the length ratio between a therapist reply and its immediately preceding client utterance, which shows how much longer the therapist \"talks in return\". As illustrated in Figure 9, Reflection has smaller length ratios in high-quality MI than in low-quality MI (e.g., for high-quality MI, smaller length ratios near the bottom of the Y-axis dominate the distribution), while Question shows the opposite, both of which are in line with the previous observation of the absolute lengths of Reflection and Question utterances in Figure 8. However, the Input length ratios are generally larger in high-quality MI sessions than in low-quality ones, which could be attributed to the fact that an MI-adherent therapist usually asks for permission first before providing input. More specifically, the therapist might say \"May I explain to you what those numbers in your blood test results mean?\", and the client would simply say \"Yes\" or \"Sure, why not\", before the therapist replies with a substantially longer Input utterance, thus leading to a larger utterance length ratio.