# Development of Smart and Lean Pick-and-Place System Using EfficientDet-Lite for Custom Dataset
## 3 Results
### Statistical Analysis on Variation of Batch Size  
As we observed in Table 14 above, the Average APs of Batch4 and Batch8 are quite similar. Therefore, a statistical analysis is conducted to see whether there is a significant difference between the two groups of values. We utilize the Mann-Whitney U method as it is one of the most commonly used non-parametric statistical tests [27]. Developed by [PERSON] in 1947, this non-parametric test is frequently used for small samples of data that are not normally distributed [28].  
In Mann-Whitney U test, the null hypothesis states that the medians of the two respective groups are not different. As for the alternative hypothesis, it states that one median is larger than the other or that the two medians differ. If the null hypothesis is not rejected, it means that the median of each group of observations is similar. If the null hypothesis is rejected, it means the two medians differ.  
Figure 11: Comparison of Average Precision across Efficientdet-Lite models.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Batch Size**} & \multirow{2}{*}{**TFLite Model**} & **Yellow** & **Yellow** & **Red** & **Red** & **Blue** & **Blue** \\  & & **Cube** & **Cylinder** & **Cube** & **Cylinder** & **Cube** & **Cylinder** \\  & & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** \\ \hline
4 & & 72.1 & 47.9 & 66.2 & 62.7 & 63.4 & 59.1 \\
8 & EfficientDet-Lite0 & 64.4 & 53.2 & 71.4 & 64.8 & 62.2 & 59.9 \\
16 & & 66.3 & 40.2 & 73.2 & 56.6 & 55.6 & 54.4 \\ \hline
4 & & 56.9 & 72.5 & 68.6 & 68.1 & 63.9 & 71.4 \\
8 & EfficientDet-Lite1 & 73.7 & 50.3 & 70.4 & 64.0 & 63.8 & 59.3 \\
16 & & 55.5 & 40.7 & 58.2 & 53.9 & 49.6 & 50.7 \\ \hline
4 & & 73.5 & 62.4 & 72.3 & 68.4 & 63.3 & 70.8 \\
8 & EfficientDet-Lite2 & 70.8 & 59.0 & 75.8 & 63.0 & 63.8 & 70.3 \\
16 & & 67.7 & 49.2 & 70.7 & 55.5 & 58.3 & 56.8 \\ \hline
4 & & 72.5 & 57.6 & 73.8 & 66.0 & 63.1 & 68.4 \\
8 & EfficientDet-Lite3 & 69.9 & 57.6 & 71.8 & 68.9 & 62.5 & 67.2 \\
16 & & 59.3 & 54.7 & 66.0 & 57.4 & 55.5 & 53.3 \\ \hline \multicolumn{2}{c}{Average of APs} & 66.9 & 53.8 & 69.9 & 62.4 & 60.4 & 61.8 \\ Standard Deviation of APs & 6.24 & 8.69 & 4.48 & 5.09 & 4.434 & 7.13 \\ \hline \hline \end{tabular}
\end{table}
Table 15: Average Precision according to workpieces.  
We apply the Mann-Whitney U test to our Batch4 and Batch8 as the number of samples are small [29], less than 30, and the AP results are not normally distributed. Our null hypothesis (H0) and alternative hypothesis (H1) follow:  
**H0**. _The median of APs is equal between Batch4 and Batch8 APs._  
**H1**. _The median of APs is not equal between Batch4 and Batch8 APs._  
Using SciPy which is a Python library used for scientific computing and technical computing, we obtain a \(p\)-value of 0.448. Since the \(p\)-value (0.448) is above the 0.05 significance level, we fail to reject the null hypothesis.  
We conclude there is not enough evidence to suggest a significant difference in medians between the two datasets. As the standard deviation only differs by 0.008, we recommend using Batch8 instead of Batch4 for faster training and evaluation.