# The Use of Transfer Learning for Activity Recognition in Instances of Heterogeneous Sensing
## 7 Results
### Teacher/Learner  
As introduced early, to evaluate the performance of the T/L approach a teacher and a learner model were defined. Derived from the baseline performance achieved by the AR Image model which reached an average classification accuracy of 95.3%; representing a difference of 4.3% and 26.8% compared to the inertial-learner model and audio-learner, respectively. The AR image model was defined as the teacher model underlined in this evaluation.  
Hence, to evaluate the performance of the Learner models, two experiments were undertaken. Firstly, one experiment where the AR inertial model played the role as a learner, followed by the second experiment, in which the AR audio model played the role as learner.  
Results from the first experiment consisting of training the inertial-learner model over the teacher's are presented in Table 7. The table shows the outcome from four sub-datasets T/L100, T/L075, T/L050, and T/L025, which represents the amount of labelled data shared by the learner model (i.e., 100%, 75%, 50%, and 25%), as rationalised in Section 4.1.  
The table contrasts the baseline against the performance from the T/L classification accuracy when the AR inertial model adopted the role as a learner. As it can be observed, the highest performance was reached when training under the alternative T/L075 (93.4%), with a difference of 2.5% compared to the baseline (91.0%).  
Results from the second experiment consisting of training the audio-learner model over the teacher's are presented in Table 8. As it can be observed, in this experiment the highest performance was reached when training under the alternative T/L075 (72.4%), with a difference of 3.7% compared to the baseline (68.5%).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Subjects** & **Inertial-Learner Baseline** & **T/L100** & **T/L075** & **T/L050** & **T/L025** \\ \hline S01 & 95.2 & 95.9 & **95.9** & 95.4 & 95.5 \\ S02 & 96.2 & 99.1 & **99.0** & 99.0 & 99.0 \\ S03 & 91.7 & 93.2 & **93.2** & 93.1 & 92.9 \\ S04 & 90.2 & 91.4 & **92.2** & 92.2 & 92.3 \\ S05 & 88.8 & 84.6 & **91.6** & 89.4 & 86.1 \\ S06 & 92.9 & 93.5 & **94.7** & 94.6 & 95.0 \\ S07 & 89.9 & 88.7 & **92.8** & 92.8 & 92.3 \\ S08 & 90.6 & 92.8 & **92.1** & 92.5 & 92.8 \\ S09 & 86.8 & 89.0 & **91.7** & 91.8 & 91.5 \\ S10 & 87.5 & 83.8 & **90.2** & 89.5 & 86.2 \\ \hline
**Average** & 91.0 & **91.2** & **93.4** & 93.0 & 92.3 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Relationship to compare the performance of the inertial-learner average classification (expressed in percentage) model trained over the T/L approach in contrast to the baseline.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Subjects** & **Audio-Learner Baseline** & **T/L100** & **T/L075** & **T/L050** & **T/L025** \\ \hline S01 & 78.9 & 78.9 & **79.0** & 78.6 & 79.3 \\ S02 & 76.7 & 77.0 & **77.8** & 77.6 & 77.7 \\ S03 & 62.7 & 65.2 & **65.7** & 65.6 & 65.8 \\ S04 & 57.0 & 68.5 & **68.9** & 68.7 & 68.6 \\ S05 & 71.3 & 67.7 & **73.0** & 70.1 & 68.3 \\ S06 & 70.1 & 70.8 & **71.8** & 70.7 & 70.7 \\ S07 & 62.8 & 71.3 & **73.3** & 72.8 & 72.0 \\ S08 & 67.2 & 68.0 & **68.9** & 67.8 & 68.0 \\ S09 & 69.0 & 71.0 & **72.9** & 73.0 & 72.3 \\ S10 & 69.0 & 65.3 & **70.9** & 70.1 & 68.3 \\ \hline
**Average** & 68.5 & 70.4 & **72.2** & 71.5 & 71.1 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Relationship to compare the performance of the audio-learner average classification (expressed in percentage) model trained over the T/L approach in contrast to the baseline.