## 4 Evaluation and Analysis
### Results  
Tables 1-5 demonstrates the results of our activity recognition approach. Table 1 and Figure 4 demonstrate the percentage of activities that are correctly recognized. For standing and sitting activities, we achieved 5% more recognition rate using j48 than the LR. MLP achieve 2% better recognition rate than j48 for both activities. For downstairs activity, using j48, we achieve 13% more recognition rate than LR, while MLP achieves 6% more recognition rate than j48. For walking activity, MLP achieves 1% and 2% more recognition rate than LR and j48. For upstairs, using j48, we achieve 14% more recognition rate than LR, while MLP achieves 10% more recognition rate than j48. For jogging activity, using j48, we achieve 1% and 2% better recognition rate than LR and MLP.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **j48** & **LR** & **MLP** \\ \hline Standing & 91.5 & 86.6 & 93.7 \\ Sitting & 91.2 & 85.5 & 92.0 \\ Downstairs & 65.7 & 52.1 & 71.5 \\ Walking & 88.3 & 91.0 & 92.5 \\ Upstairs & 75.6 & 67.5 & 79.3 \\ Jogging & 96.2 & 95.3 & 94.0 \\ Overall & 85.0 & 79.6 & 87.2 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Recognition rate comparison of j48, LR and MLP classifier with respect to each activity.  
Table 2 and Figure 5 demonstrate the recognition in percentage. As a conclusion using MLP, we achieve 87% accuracy which is 2% and 8% better than j48 and LR respectively. For further experiments, we only use MLP classifier for axis analysis Section 4.3 and comparative analysis Section 4.4 with the state-of-the-art.  
Figure 6 shows the correctly classified activities concerning misclassified activities using the Decision Tree (j48) classifier. 19.5% of upstairs instances are misclassified as downstairs and 24.5% instances of downstairs are misclassified as upstairs. The jogging activity is misclassified 2.5% as walking, while the standing, sitting and walking are classified with minor confusions.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Precision** & **Recall** & **F-Score** & **Accuracy** \\ \hline j48 & 83.2 & 85.0 & 84.0 & 85.0 \\ LR & 78.1 & 79.6 & 78.1 & 79.6 \\ MLP & 86.7 & 87.2 & 86.9 & 87.2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Comparison of evaluation measures with respect to j48, LR and MLP classifier.  
Figure 4: Recognition rate comparison of j48, LR and MLP classifier concerning each activity.  
Figure 5: Comparison of evaluation measures with respect to j48, LR and MLP classifier.  
Figure 7 shows the correctly classified activities concerning misclassified activities using the Linear Regression (LG) classifier. 24.5% of upstairs instances are misclassified as downstairs and 24% of downstairs instances are misclassified as upstairs. The jogging activity is misclassified 3.7% as walking and 1.0 as standing, while the standing, sitting and walking are classified with minor confusions.  
Figure 8 shows the correctly classified activities concerning misclassified activities using the Multilayer Perceptron (MLP) classifier. 15.5% of upstairs instances are misclassified as downstairs and 22.5% instances of downstairs are misclassified as upstairs. The jogging activity is misclassified 4.0% as walking and 2.0 as standing, while the standing, sitting and walking are classified with minor confusions. It is observed that MLP classifier is an optimal choice amongst other  
Figure 6: Confusion matrix of activity recognition using j48 classifier.  
Figure 7: Confusion matrix of activity recognition using LG classifier.