SG Money Tree: Do US indices affect STI?

Well, it's a popular notion on HWZ forums that STI follows the US stock market, and people like to predict the STI movement based on the last closing of the US indices. So I tested that with data from Yahoo Finance ranging from Dec 2010 to Dec 2015, using Spearman's correlation between ES3 and a number of indices.

Name	Symbol	Spearman Correlation
Lyxor AsiaIT US$	NF4.SI	0.948438693
Lyxor World US$	H1P.SI	0.922792769
LYXOR Asia EX US$	G1K.SI	0.914623755
Lyxor AsiaCS US$	NF6.SI	0.902705567
Lyxor HSI US$	A9B.SI	0.879719834
Lyxor USDJIA US$	JC6.SI	0.870809236
Lyxor Asia US$	P60.SI	0.846190831
Lyxor Japan US$	CW4.SI	0.836158667
Lyxor Nasdaq US$	H1Q.SI	0.787960823
Lyxor Europe US$	JC5.SI	0.762374024
Lyxor AsiaRE US$	MT7.SI	0.75007067
Lyxor Taiwan US$	A9A.SI	0.733011747
Lyxor ThaiSET US$	P2P.SI	0.638932037
Lyxor MSIndia US$	G1N.SI	0.605130262
Lyxor ChinaH US$	P58.SI	0.528158153
Lyxor MAL US$	G1M.SI	0.487952323
Lyxor Korea US$	AO9.SI	0.418580403
Lyxor EM Mkt US$	H1N.SI	0.27739576
Lyxor Indonesia US$	P2Q.SI	0.232005556
Lyxor LATAM US$	H1O.SI	-0.450758975
Lyxor Russia US$	JC7.SI	-0.547590704
Lyxor Cmdty US$	A0W.SI	-0.657178453
Lyxor CRBxEny US$	G1O.SI	-0.665450671

So seems that the correlation with Nasdaq is 0.788, which is pretty high. Note some limitations: 1. no adjustments for currency, 2. Lyxor ETFs are not that liquid here, 3. Short timeframe.