"Alpha" is the difference between how your portfolio grows or shrinks with respect to overall market. If you have positive and big alpha that means, however the market moves you should be on the plus side.
For example if you "know" that blockchain will be big, and some projects will certainly do better than the others, you can buy the better ones and sell the bad ones. The difference will be your gain. To learn more about hedging Khan's Academy has good videos about hedge funds. I recommend them.
I collected prices in 5 minute intervals for 300 coins, and got the history in between Jan 1st and Aug 31st, 2017. So this doesn't include the Chinese FUD. When a price is not available the tool (in Python) disregarded and didn't count that price in calculations. The correlation type is Pearson.
After calculating the correlations, for the sake of simplicity I selected and showed here 40 coins with most volume traded on exchanges.
Link to better resolution: http://imgur.com/a/aYraw
White belt (USDT) has almost no relation to others. Mixed red-green belts are "independent" coins.
Mean correlations:
Disregarding USDT which is uncorrelated by design, we have BCH, EOS and BNB on top.
Coin, Mean correlation to overall market
BCH 0.102151
EOS 0.107354
USDT 0.112928
BNB 0.234794
IOT 0.322519
ADX 0.358795
MCO 0.407021
PAY 0.420214
OMG 0.496051
ANS 0.520597
QTUM 0.537294
XLM 0.565048
DGB 0.580644
LBC 0.601964
SC 0.604193
BTS 0.635785
NXT 0.640968
XVG 0.642369
DOGE 0.650372
ETC 0.660522
GAME 0.660655
BCN 0.667741
XMR 0.691249
XRP 0.692115
GNT 0.692524
STEEM 0.698942
STRAT 0.718324
LSK 0.737653
LTC 0.739248
DCR 0.742341
DASH 0.749734
SYS 0.760158
BTC 0.763944
XEM 0.764458
REP 0.777097
WAVES 0.788526
ZEC 0.792942
FCT 0.805125
MAID 0.810819
ETH 0.828468
We can say the coins on top have their own way of moving in the markets. Or if sometimes they move in the opposite direction to others, the correlation value gets lower and lower. If the coin is moving as everybody else, the value gets higher. Interestingly ETH moves very similar to whole market. Possibly because all the tokens are related to it.
We know that BCH is THE alternative to bitcoin, so no surprise there. Since BTC has high correlation, alternative of it must have low correlation.
Interestingly EOS came second. Why do you think is this the case? STEEM and BTS are not even close. My opinion is a lot of tokens are in ETH and EOS is the alternative of ETH, hence it has one of the lowest correlations.