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Topic: Satoshi Dice -- Statistical Analysis - page 60. (Read 192889 times)

donator
Activity: 2058
Merit: 1054
November 01, 2012, 02:48:59 PM
Ok. We have a total of 79,000 bets resulting in a total profit of -5121 BTC. If we assume the bets are fixed and their results are variable, then the mean profit is 1285 BTC and the variance is 3084000 BTC^2. This means the result is 3.65 sd below the mean.

The probability for a normal random variable to be this low is 0.000132. We need to correct for selection bias; there may be better ways to do it but multiplying by 1000 would be the right ballpark (the effective number of choices for the period to investigate). This means that there would be about 13% chance of getting results this bad somewhere on the graph. This means they indeed have some bad luck, but not so much so to indicate something may be wrong.

1000 seems too big to me.

there have been 1.5m bets in total so 20 seems more reasonable than 1000.
This has very little to do with the number of bets (in particular you seem to want to use the base-2 log but I see no justification for that. Probabilities are not on the same scale as information bits). It's about how many choices there are to choose the period to analyze. With a very simplistic calculation, you have 180 choices for the start date and about 10 choices for the length, which would come up as 1800. Now you have to correct for the correlations, the fact that we didn't actually go and optimize the worst period, etc. Maybe something like 500 or even less is more appropriate but again this is just a back-of-the-envelope calculation. I agree that it is unusual enough to look into it further.
sr. member
Activity: 438
Merit: 291
November 01, 2012, 05:41:07 AM
Ok. We have a total of 79,000 bets resulting in a total profit of -5121 BTC. If we assume the bets are fixed and their results are variable, then the mean profit is 1285 BTC and the variance is 3084000 BTC^2. This means the result is 3.65 sd below the mean.

The probability for a normal random variable to be this low is 0.000132. We need to correct for selection bias; there may be better ways to do it but multiplying by 1000 would be the right ballpark (the effective number of choices for the period to investigate). This means that there would be about 13% chance of getting results this bad somewhere on the graph. This means they indeed have some bad luck, but not so much so to indicate something may be wrong.

1000 seems too big to me.

there have been 1.5m bets in total so 20 seems more reasonable than 1000.
donator
Activity: 2058
Merit: 1054
October 31, 2012, 05:57:10 PM
Ok. We have a total of 79,000 bets resulting in a total profit of -5121 BTC. If we assume the bets are fixed and their results are variable, then the mean profit is 1285 BTC and the variance is 3084000 BTC^2. This means the result is 3.65 sd below the mean.

The probability for a normal random variable to be this low is 0.000132. We need to correct for selection bias; there may be better ways to do it but multiplying by 1000 would be the right ballpark (the effective number of choices for the period to investigate). This means that there would be about 13% chance of getting results this bad somewhere on the graph. This means they indeed have some bad luck, but not so much so to indicate something may be wrong.

It just occurred to me that not all the bets are independent events.  You can't tell from the data I provided, but it's possible to place multiple bets within a single transaction.  All such bets get the same 'magic number'.

I don't know what impact that would have on your calculations.  If you like, I could add a txid to each bet so you can tell which are grouped with which.
It would be a bit more work to take into account grouped bets. But the impact of the fact that those exist is that the variance will be higher, meaning the results are even more plausible.

I think it would be fine to try to carry out a more sophisticated statistical test, and/or ask the operators if they know of anything which could cause a problem. But if not that's also fine, the results are within the realm of possibility.
legendary
Activity: 2940
Merit: 1333
October 31, 2012, 01:59:04 PM
Quote
Results: 2012-Oct-31 10:56am (up to block 205877)

   Address  Target   Should Win |    #Bets |       Win        |  Lose  | Refunds |   BTC In   |  BTC Out   |  Refund  |   Profit  |   RTP 
--------------------------------------------------------------------------------------------------------------------------------------------
 1dice1e6p       1      0.00002 |    32390 |      0 (0.00000) |  31955 |     435 |     229.18 |       0.01 |    37.05 |    229.16 |   0.008
 1dice1Qf4       2      0.00003 |     2101 |      0 (0.00000) |   2015 |      86 |      29.39 |       0.00 |    10.45 |     29.39 |   0.006
 1dice2pxm       4      0.00006 |     3210 |      0 (0.00000) |   3168 |      42 |      41.70 |       0.03 |     5.65 |     41.67 |   0.075
 1dice2vQo       8      0.00012 |     3925 |      2 (0.00052) |   3879 |      44 |      71.75 |      16.06 |     5.65 |     55.69 |  22.391
 1dice2WmR      16      0.00024 |     5448 |      1 (0.00018) |   5408 |      39 |     160.06 |       4.29 |     8.40 |    155.77 |   2.680
 1dice2xkj      32      0.00049 |     7068 |      3 (0.00043) |   7053 |      12 |     464.66 |     303.36 |     1.29 |    161.29 |  65.287
 1dice2zdo      64      0.00098 |     8929 |      8 (0.00090) |   8897 |      24 |     737.83 |     124.60 |    55.64 |    613.22 |  16.888
 1dice37Ee     128      0.00195 |    10925 |     19 (0.00175) |  10849 |      57 |    1658.28 |    1274.79 |    48.25 |    383.49 |  76.874
 1dice3jkp     256      0.00391 |    12459 |     55 (0.00442) |  12387 |      17 |    1840.81 |    2621.90 |    13.12 |   -781.08 | 142.432
 1dice4J1m     512      0.00781 |    18926 |    143 (0.00756) |  18772 |      11 |    3548.87 |    3432.83 |     9.35 |    116.03 |  96.730
 1dice5wwE    1000      0.01526 |    40265 |    615 (0.01528) |  39637 |      13 |   10024.92 |    9652.85 |     1.80 |    372.07 |  96.289
 1dice61SN    1500      0.02289 |    17552 |    418 (0.02383) |  17126 |       8 |    5680.16 |    5969.40 |    15.00 |   -289.23 | 105.092
 1dice6DPt    2000      0.03052 |    25267 |    804 (0.03183) |  24459 |       4 |    6404.69 |    6116.42 |     9.24 |    288.26 |  95.499
 1dice6gJg    3000      0.04578 |    18013 |    835 (0.04638) |  17170 |       8 |    7762.14 |    9127.40 |    24.99 |  -1365.25 | 117.589
 1dice6GV5    4000      0.06104 |    17885 |   1116 (0.06241) |  16765 |       4 |    5129.26 |    4751.49 |    31.20 |    377.76 |  92.635
 1dice6wBx    6000      0.09155 |    24079 |   2256 (0.09377) |  21804 |      19 |   11072.34 |   11275.17 |     7.01 |   -202.83 | 101.832
 1dice6YgE    8000      0.12207 |    97633 |  12012 (0.12306) |  85597 |      24 |   13373.28 |   11887.83 |     0.00 |   1485.45 |  88.892
 1dice7EYz   12000      0.18311 |    24292 |   4527 (0.18649) |  19748 |      17 |    9412.69 |    9708.52 |    14.50 |   -295.83 | 103.143
 1dice7fUk   16000      0.24414 |   110685 |  27026 (0.24423) |  83633 |      26 |   65814.07 |   64973.82 |   566.79 |    840.25 |  98.723
 1dice7W2A   24000      0.36621 |    78812 |  28984 (0.36799) |  49779 |      49 |   55512.94 |   56799.35 |   212.64 |  -1286.41 | 102.317
 1dice8EMZ   32000      0.48828 |   643802 | 314481 (0.48882) | 328860 |     461 |  376146.46 |  373287.86 |  2923.41 |   2858.59 |  99.240
 1dice97EC   32768      0.50000 |   232858 | 116146 (0.49920) | 116520 |     192 |  221882.56 |  219108.13 |  1709.77 |   2774.42 |  98.750
 1dice9wcM   48000      0.73242 |   171071 | 125890 (0.73624) |  45100 |      81 |  167442.96 |  165379.64 |   704.58 |   2063.31 |  98.768
 1dicec9k7   52000      0.79346 |    17441 |  13873 (0.79602) |   3555 |      13 |   28467.20 |   28490.24 |  1187.00 |    -23.03 | 100.081
 1dicegEAr   56000      0.85449 |    16236 |  13903 (0.85752) |   2310 |      23 |   26834.11 |   26711.24 |   400.00 |    122.86 |  99.542
 1diceDCd2   60000      0.91553 |     7917 |   7244 (0.91580) |    666 |       7 |   20225.02 |   20175.20 |     0.00 |     49.81 |  99.754
 1dice9wVt   64000      0.97656 |     8306 |   7995 (0.98002) |    163 |     148 |   17934.44 |   17654.39 |   239.21 |    280.04 |  98.439
--------------------------------------------------------------------------------------------------------------------------------------------
           small (bets < 4 BTC) |  1604287 | 651548           | 951095 |    1644 |  397936.35 |  390164.85 |   157.60 |   7771.49 |  98.047
            big (bets >= 4 BTC) |    53208 |  26808           |  26180 |     220 |  659965.53 |  658682.09 |  8084.50 |   1283.43 |  99.806
--------------------------------------------------------------------------------------------------------------------------------------------
                                |  1657495 | 678356           | 977275 |    1864 | 1057901.89 | 1048846.95 |  8242.11 |   9054.93 |  99.144
--------------------------------------------------------------------------------------------------------------------------------------------

SD Profit before fees:       9054.93751467 BTC (0.856%)
Cumulative Fees Paid:         851.09407500 BTC
SD Profit after fees:        8203.84343967 BTC (0.775%)
----
Since Satoshi Dice started, there have been:
Blockchain Tx:  5590392  :  SatoshiDice Tx: 3076136  (55.0%)
Blockchain MB:  2355.1  :  SatoshiDice Tx: 1257.2  (53.4%)

legendary
Activity: 2940
Merit: 1333
October 31, 2012, 01:22:55 PM
Ok. We have a total of 79,000 bets resulting in a total profit of -5121 BTC. If we assume the bets are fixed and their results are variable, then the mean profit is 1285 BTC and the variance is 3084000 BTC^2. This means the result is 3.65 sd below the mean.

The probability for a normal random variable to be this low is 0.000132. We need to correct for selection bias; there may be better ways to do it but multiplying by 1000 would be the right ballpark (the effective number of choices for the period to investigate). This means that there would be about 13% chance of getting results this bad somewhere on the graph. This means they indeed have some bad luck, but not so much so to indicate something may be wrong.

It just occurred to me that not all the bets are independent events.  You can't tell from the data I provided, but it's possible to place multiple bets within a single transaction.  All such bets get the same 'magic number'.

I don't know what impact that would have on your calculations.  If you like, I could add a txid to each bet so you can tell which are grouped with which.
donator
Activity: 2058
Merit: 1054
October 31, 2012, 08:32:45 AM
Ok. We have a total of 79,000 bets resulting in a total profit of -5121 BTC. If we assume the bets are fixed and their results are variable, then the mean profit is 1285 BTC and the variance is 3084000 BTC^2. This means the result is 3.65 sd below the mean.

The probability for a normal random variable to be this low is 0.000132. We need to correct for selection bias; there may be better ways to do it but multiplying by 1000 would be the right ballpark (the effective number of choices for the period to investigate). This means that there would be about 13% chance of getting results this bad somewhere on the graph. This means they indeed have some bad luck, but not so much so to indicate something may be wrong.
legendary
Activity: 2940
Merit: 1333
October 30, 2012, 04:42:13 PM
It is indeed important. If we assume the extreme that all bets are either 0 or the max bet, the variance increases 100-fold which means that the result is only about 1.2 sd below the mean. A list of bets can resolve this particular issue.

What fields do you want to see per bet?

block number, date, bet type, stake, result, return?

Anything else?
These should be enough.

OK, I made a text file of the bets from the last 1500 blocks or so (since the decline started) here (both the same, the 2nd is gzip compressed)

http://dooglus.rincevent.net/random/details.txt (4955 KB)
http://dooglus.rincevent.net/random/details.txt.gz (299 KB)

In doing so, I noticed that the SD bottom line has dropped further since this morning's stats post.  Now it's:

SD Profit after fees:        8122.86383142 BTC (0.772%)

Here's the first 7 lines from the file, where things started going downhill:

Code:
204245,Sat Oct 20 20:33:17 2012,6000,WIN,1.00000000,10.66502266
204245,Sat Oct 20 20:33:17 2012,6000,WIN,1.00000000,10.66502266
204245,Sat Oct 20 20:33:17 2012,12000,WIN,0.30000000,1.60007840
204246,Sat Oct 20 20:35:27 2012,1000,WIN,2.00000000,127.93577200
204246,Sat Oct 20 20:35:27 2012,512,WIN,2.00000000,249.86550000
204246,Sat Oct 20 20:35:27 2012,1500,WIN,1.00000000,42.64659066
204246,Sat Oct 20 20:35:27 2012,32000,LOSE,0.50000000,0.00200000

That's block_number,time_and_date,target,result,stake,return

So the first line is a "lessthan 6000" bet winning, and so is the 2nd line.  2 separate bets, both winning:

http://www.satoshidice.com/lookup.php?tx=0a4d8505e11b3af56f31016c8d738927a0a62aececc0b0e8c81dd8d471ef8f83
http://www.satoshidice.com/lookup.php?tx=b6723d3c2227c288910088dff5f332fff675014b12e46dddb75278aa1efc8d03
donator
Activity: 2058
Merit: 1054
October 30, 2012, 03:19:06 PM
It is indeed important. If we assume the extreme that all bets are either 0 or the max bet, the variance increases 100-fold which means that the result is only about 1.2 sd below the mean. A list of bets can resolve this particular issue.

What fields do you want to see per bet?

block number, date, bet type, stake, result, return?

Anything else?
These should be enough.
legendary
Activity: 2940
Merit: 1333
October 30, 2012, 03:17:31 PM
It is indeed important. If we assume the extreme that all bets are either 0 or the max bet, the variance increases 100-fold which means that the result is only about 1.2 sd below the mean. A list of bets can resolve this particular issue.

What fields do you want to see per bet?

block number, date, bet type, stake, result, return?

Anything else?
donator
Activity: 2058
Merit: 1054
October 30, 2012, 03:09:59 PM
For each type of bet I calculated the average amount put in, and assumed the actual bets are distributed uniformly from 0 to twice the average.

I don't know how important this is, but I doubt that's at all close to the actual distribution.  I would expect tiny bets to be the vast majority of bets placed.  I suspect that there are thousands of sub-1 BTC bets, and very few larger bets.

I will make a text file available detailing all the bets processed in the last couple of weeks, so that you can make a proper analysis.

But first I have to go light some fires and let a little dog out to pee.  Smiley
It is indeed important. If we assume the extreme that all bets are either 0 or the max bet, the variance increases 100-fold which means that the result is only about 1.2 sd below the mean. A list of bets can resolve this particular issue.

Honestly it looks like its in the realm of possibility to me. Compare it to the 11/08 jump.
That's what I think too. I did those calculations in an attempt to demonstrate that this is indeed nothing to worry about (not the best way to do science, but my methodology was simple enough not to be influenced by my prejudice). Which is why I was a bit surprised by my result, but variance in the bet amounts may explain them away.
hero member
Activity: 784
Merit: 1000
0xFB0D8D1534241423
October 30, 2012, 02:50:52 PM
Wheee!

Honestly it looks like its in the realm of possibility to me. Compare it to the 11/08 jump.
legendary
Activity: 2940
Merit: 1333
October 30, 2012, 02:36:54 PM
Quote
Results: 2012-Oct-30 10:58am (up to block 205738)

   Address  Target   Should Win |    #Bets |       Win        |  Lose  | Refunds |   BTC In   |  BTC Out   |  Refund  |   Profit  |   RTP 
--------------------------------------------------------------------------------------------------------------------------------------------
 1dice1e6p       1      0.00002 |    31845 |      0 (0.00000) |  31414 |     431 |     226.76 |       0.01 |    36.82 |    226.74 |   0.009
 1dice1Qf4       2      0.00003 |     2093 |      0 (0.00000) |   2009 |      84 |      29.37 |       0.00 |    10.29 |     29.37 |   0.006
 1dice2pxm       4      0.00006 |     3192 |      0 (0.00000) |   3151 |      41 |      40.70 |       0.03 |     5.45 |     40.67 |   0.077
 1dice2vQo       8      0.00012 |     3918 |      2 (0.00052) |   3872 |      44 |      71.75 |      16.06 |     5.65 |     55.68 |  22.393
 1dice2WmR      16      0.00024 |     5441 |      1 (0.00019) |   5401 |      39 |     159.98 |       4.29 |     8.40 |    155.69 |   2.682
 1dice2xkj      32      0.00049 |     7057 |      3 (0.00043) |   7042 |      12 |     464.45 |     303.36 |     1.29 |    161.08 |  65.317
 1dice2zdo      64      0.00098 |     8888 |      8 (0.00090) |   8857 |      23 |     736.57 |     124.60 |    55.64 |    611.97 |  16.916
 1dice37Ee     128      0.00195 |    10911 |     19 (0.00175) |  10835 |      57 |    1653.16 |    1274.76 |    48.25 |    378.39 |  77.111
 1dice3jkp     256      0.00391 |    12125 |     55 (0.00454) |  12056 |      14 |    1837.42 |    2621.90 |    13.11 |   -784.47 | 142.694
 1dice4J1m     512      0.00781 |    18847 |    143 (0.00759) |  18693 |      11 |    3545.36 |    3432.83 |     9.35 |    112.53 |  96.826
 1dice5wwE    1000      0.01526 |    39924 |    610 (0.01528) |  39301 |      13 |    9978.69 |    9650.07 |     1.80 |    328.62 |  96.707
 1dice61SN    1500      0.02289 |    17535 |    418 (0.02385) |  17109 |       8 |    5654.31 |    5969.28 |    15.00 |   -314.96 | 105.570
 1dice6DPt    2000      0.03052 |    25239 |    803 (0.03182) |  24432 |       4 |    6402.66 |    6116.10 |     9.24 |    286.55 |  95.524
 1dice6gJg    3000      0.04578 |    17976 |    835 (0.04647) |  17133 |       8 |    7757.95 |    9127.38 |    24.99 |  -1369.43 | 117.652
 1dice6GV5    4000      0.06104 |    17851 |   1116 (0.06253) |  16731 |       4 |    5125.32 |    4751.48 |    31.20 |    373.83 |  92.706
 1dice6wBx    6000      0.09155 |    23965 |   2243 (0.09367) |  21703 |      19 |   11016.96 |   11152.09 |     7.01 |   -135.12 | 101.227
 1dice6YgE    8000      0.12207 |    97261 |  11968 (0.12308) |  85269 |      24 |   13225.64 |   11725.18 |     0.00 |   1500.45 |  88.655
 1dice7EYz   12000      0.18311 |    24236 |   4514 (0.18637) |  19706 |      16 |    9383.85 |    9664.49 |    14.50 |   -280.63 | 102.991
 1dice7fUk   16000      0.24414 |   109717 |  26794 (0.24427) |  82897 |      26 |   65214.41 |   64342.94 |   566.79 |    871.47 |  98.664
 1dice7W2A   24000      0.36621 |    77988 |  28677 (0.36794) |  49262 |      49 |   54512.85 |   55785.23 |   212.64 |  -1272.37 | 102.334
 1dice8EMZ   32000      0.48828 |   643035 | 314131 (0.48886) | 328444 |     460 |  374595.21 |  371536.31 |  2673.41 |   3058.90 |  99.183
 1dice97EC   32768      0.50000 |   229582 | 114547 (0.49935) | 114843 |     192 |  219125.35 |  216348.79 |  1709.77 |   2776.55 |  98.733
 1dice9wcM   48000      0.73242 |   170660 | 125592 (0.73627) |  44987 |      81 |  167267.34 |  165222.79 |   704.58 |   2044.55 |  98.778
 1dicec9k7   52000      0.79346 |    17385 |  13829 (0.79605) |   3543 |      13 |   28362.54 |   28372.86 |  1187.00 |    -10.32 | 100.036
 1dicegEAr   56000      0.85449 |    16139 |  13821 (0.85759) |   2295 |      23 |   26514.22 |   26345.44 |   400.00 |    168.77 |  99.363
 1diceDCd2   60000      0.91553 |     7798 |   7143 (0.91683) |    648 |       7 |   19631.18 |   19592.08 |     0.00 |     39.10 |  99.801
 1dice9wVt   64000      0.97656 |     8289 |   7978 (0.97998) |    163 |     148 |   17910.32 |   17630.18 |   239.21 |    280.14 |  98.436
--------------------------------------------------------------------------------------------------------------------------------------------
           small (bets < 4 BTC) |  1596110 | 648642           | 945836 |    1632 |  396027.19 |  388408.86 |   157.02 |   7618.33 |  98.076
            big (bets >= 4 BTC) |    52787 |  26608           |  25960 |     219 |  654417.26 |  652701.78 |  7834.50 |   1715.48 |  99.738
--------------------------------------------------------------------------------------------------------------------------------------------
                                |  1648897 | 675250           | 971796 |    1851 | 1050444.46 | 1041110.64 |  7991.53 |   9333.81 |  99.111
--------------------------------------------------------------------------------------------------------------------------------------------

SD Profit before fees:       9333.81729799 BTC (0.889%)
Cumulative Fees Paid:         842.47867500 BTC
SD Profit after fees:        8491.33862299 BTC (0.808%)
----
Since Satoshi Dice started, there have been:
Blockchain Tx:  5561537  :  SatoshiDice Tx: 3060185  (55.0%)
Blockchain MB:  2342.5  :  SatoshiDice Tx: 1250.5  (53.4%)

legendary
Activity: 2940
Merit: 1333
October 30, 2012, 02:35:06 PM
For each type of bet I calculated the average amount put in, and assumed the actual bets are distributed uniformly from 0 to twice the average.

I don't know how important this is, but I doubt that's at all close to the actual distribution.  I would expect tiny bets to be the vast majority of bets placed.  I suspect that there are thousands of sub-1 BTC bets, and very few larger bets.

I will make a text file available detailing all the bets processed in the last couple of weeks, so that you can make a proper analysis.

But first I have to go light some fires and let a little dog out to pee.  Smiley
hero member
Activity: 488
Merit: 500
October 30, 2012, 12:27:34 PM
Secret leaked?
legendary
Activity: 2142
Merit: 1009
Newbie
October 30, 2012, 10:46:32 AM
Now, of course picking the most suspicious-looking 9-day period among half a year of statistics would skew the results. But still it would only be reasonable to get maybe 4 or 5 sd difference. 12.5 is just too much, and warrants further investigation.

Max bets where changed recently. This could change the pattern of bets and winnings.
donator
Activity: 2058
Merit: 1054
October 30, 2012, 10:21:52 AM
I did a few hasty calculations, with lots of assumptions and room for errors along the way, but:

I took your table for Oct 29 stats and subtracted from it the Oct 20 stats, to get the stats for the period in question.

For each type of bet I calculated the average amount put in, and assumed the actual bets are distributed uniformly from 0 to twice the average.

From this I calculated the mean and variance of the profit from each type, summed over all types and compared it to the actual total profit.

I got a result which is 12.5 standard deviations below the mean (and we're talking about an approximately normal distribution).

Now, of course picking the most suspicious-looking 9-day period among half a year of statistics would skew the results. But still it would only be reasonable to get maybe 4 or 5 sd difference. 12.5 is just too much, and warrants further investigation.

Again, I could be wrong about the whole thing but at least it indicates someone needs to do a more careful analysis. A better analysis can be obtained with a table of the individual bets.
donator
Activity: 2058
Merit: 1007
Poor impulse control.
October 30, 2012, 08:01:23 AM
This is starting to look weird.  The slide just isn't stopping.  What's going on here?

I looks like a random walk with drift to me. You could use the Augmented Dickey Fuller test to test if the change is likely give a null hypothesis that nothing abnormal has occurred. Or I can do it if I have time.
hero member
Activity: 488
Merit: 500
October 30, 2012, 07:53:40 AM
This is starting to look weird.  The slide just isn't stopping.  What's going on here?
Indeed this looks fishy. Given the amount of bets I am tempted to not accept this as pure coincidence/bad luck.
member
Activity: 75
Merit: 10
October 29, 2012, 03:17:30 PM
If you look at the difference between small bets and big bets, the small bets aren't winning or losing particularly well but it just seems that theres a few bigger bets that are just killing the house. If you think about it, it doesn't take alot of big winning bets to hurt the house.
legendary
Activity: 2142
Merit: 1009
Newbie
October 29, 2012, 12:29:11 PM
This is starting to look weird.  The slide just isn't stopping.  What's going on here?

Maybe PR. Maybe bad karma. Maybe just fluctuation.
Or maybe u was right regarding dividends.
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