Sentence:  Based on the findings and research designs of relevant studies done in the past (cf. Jin, 2006; Ke, 1996; Ping, 2006; Xiao, 2002), the threshold of the <WSD>character density</WSD> in this study was set at 11 strokes. 
Meaning of the word marked with <WSD> tags:  The number of strokes required to form a Chinese character.