(2) Evaluation Parameters

Let us define three evaluation parameters such as $R$ (recall factor), $P$ (precision factor) and $F$ (F-parameter) as follows:

$$R=\frac{No. \> of \> relevant \> documents \> retrieved}{No. \> of \> relevant \> documents \> in \> DB}$$ (9) (10)

$$P=\frac{No. \> of \> relevant \> documents \> retrieved}{No. \> of \> documents \> retrieved}$$ (11) (12)

$$F=\frac{(b^2+1) \cdot P \cdot R}{b^2 \cdot P+R}$$ (13)

Here, parameter $b$ in $eq$. (11) represents the relative weights of $R$ and $P$. We set $b=1$ in our experiments.