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[Guides] New Shard Drop Rate after ver1.2.25 - A Statistical Test

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Posted on 12/20/13 10:23:34 PM | Show thread starter's posts only

Edited by Hero87884419 at 12-20-2013 10:28 PM

Previously I have reported the shard drop rate (SDR) in skulled dungeon
( ... 97&page=1#pid357589).

After that I did two small scale tests after some updates to see if there were reasons to believe that SDR had change. The new update (ver1.2.25) introduced a bigger emphasis on hero shards. So it brought to my interest to test whether SDR had changed in ver1.2.25.

For my previous test, I made three assumptions:

1)The drop rates are the same across all skulled dungeons;

2)The drop rate stays constant throughout time and throughout ver1.1.3 to 1.2.1

3)Each trial is independent, ie., whether I get shards this time does not changethe probability of the next trial.

Combining my results from all the previous tests that finished 100% in dungeon D2S1, D2S2and D3S1, I have success/fail = 130/332. This means a SDR of 28% (95%confidence interval [CI]: 24~32%)

For this new test, I made two assumptions instead:

1)The drop rate stays constant during time of the day.

2)Each trial is independent, ie., whether I get shards this time does not change the probability of the next trial.

The biggest change is that I don't assume the same SDR for all dungeons but will rather test if that is the case.

To make the process faster, I decided to farm shards with my original and smurfaccounts. So the first question I asked was whether there is reason to believethat the SDR is different for each account. To test this, I raided D2S2using two accounts for 15 times each. Here is the test result:

Account1:success/fail =  6/9

Account2:success/fail =  5/10

P value from chi-square test: 0.70

The conclusion is that there is no difference of SDR for individual accounts.

Next, I started my test in four skulled dungeons: D2S1, D2S2, D3S1, D3S2. Besides recording SDR, I also kept track of whether I had casualty in heroes and troops. After 85 trials, I compared the result and found no correlation between SDR and casualty of heroes or troops (see table below, p=0.65).


No Hero casualty


Hero casualty








No shards







No Troop casualty


Troop casualty








No shards






I continued the test until I reached 100 trials for each dungeon.  Here are
thetest results:

D2S1 success/fail = 38/62; SDR = 38%, 95%CI (28%~48%)

D2S2 success/fail = 38/62; SDR = 38%, 95%CI (28%~48%)

D3S1 success/fail = 34/66; SDR = 34%, 95%CI (25%~43%)

D3S2 success/fail = 22/78; SDR = 22%, 95%CI (14%~30%)

In total, SDR remained same (Previous Success/Fail 130/332 vs New Success/Fail 132/268, P=0.12). However, to make a better comparison to my oldtest results, I have to remove the data from D3S2 because my old test result only covered D2S1 to D3S1. In this case, the SDR actually increased (130/332 vs110/190; P=0.013).

Despite the apparent low SDR in D3S2, chi-square test suggests that it is not statistically significant (P=0.051). In another word, we cannot reject the hypothesis that SDR in different dungeons are the same. However, if my test results are really within the 95%confidence interval, that is, not way off the real SDR, then there is somethingthat we should note: we can calculate an expected shard gain by multiply SDRwith shard number. For D2S1, it is 4 x 0.38 = 1.52; for D2S2,D3S1 and D3S2, it is 1.9, 2.04, 1.54, respectively. You see farming D3S2 willactually get you less shards. It is odd why SDR is particularly low in D3S2. Iwill keep tracking to 200 tests to get the SDR closer to the real number.Meanwhile, I've also started farming D4S1 and see if SDR is similar to D3S2. Iwill also track how fast I raided the dungeon as someone brought up this issue (thefaster one finishes, the higher SDR).

However, since the release of v1.2.26, dungeon has descended to a secondary sourceof shards. Nowadays it should be so easy to get 100 shards daily from monster attacks. In another words, although I propose to keep farming shards using dungeons, I actually don't have strong motivations any more.


Posted on 12/22/13 12:30:19 PM | Show thread starter's posts only

3 raids per hour for the chance to get a high amount of shards vs 1 raid every 3 hours for a chance of less shards is good enough reason for me to keep farming for slimes.

and if you happen to lose your heroes in a bad dungeon raid (which does happen) you can just do a HBM to pass the time away

Posted on 12/26/13 1:47:12 PM | Show thread starter's posts only

Thanks for sharing this valuable information :)

Posted on 1/10/14 11:34:42 AM | Show thread starter's posts only

I'm still skeptical about skull dungeon drop rates differing. It's strange to think a different dungeon will have a different rate even if they are both skulls. I still believe the rate is around 28% based on my experience, though I have no recorded any data... it just seems in that ball park for all skull dungeons I do.

Posted on 1/11/14 7:24:59 AM | Show thread starter's posts only

Am i the only one who feel that shards are getting harder to get now?

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