Hougang by-election 2012 (my thoughts)

1.disappearance of Hougang's former mp, Yaw Shin Leong

http://www.channelnewsasia.com/stories/singaporelocalnews/view/1183169/1/.html

2. resign of Sajeev Kamalasana from WP

http://theonlinecitizen.com/2012/05/sajeev-kamalasanan-resigns-from-the-workers-party/comment-page-5/#comment-372868

3.Zeng Guoyan former WP member

http://anonymousxwrites.blogspot.com/2011/04/zeng-guoyan-independent-candidate-who.html

4. quitting of Eric Tan

http://www.tremeritus.com/2011/05/13/bitter-in-fighting-in-wp-over-ncmp-seat/

What can u infer from all these sources ????????????
In what ways are #1 and #3 similar?
In what ways are #2 and #4 similar?