I spent 11 hours today in Daiku Cave on hard, and yet I didn't get a SINGLE marble. Not red, blue, white, nothing. I did however get 3 Makira magatamas of which even the NPCs don't even want because they don't sell for anything, and dissolution gives back common drop materials. Normally, Makira magatamas are a hell ranked magatama, but I'm not sure what that means (http://wikiwiki.jp/oni_giri/?%C2%E7%D2%E3%C6%B6%B7%EA). On my way to repairs, sometimes I kill random field monsters, and during my 11 hours, I got 4 marbles from the field monsters being 3 blue and 1 white. I know for a fact that killing field mobs gives those marbles like there's no tomorrow. So if you ever need common marbles like red, blue, or white, just kill field mobs, they practically spit them out. The addition of those marbles was insult to injury needless to say.
Now, let's assume every hour I took a 10 minute break for repairs/take care of what I needed to do. We can also say I took less than 30 seconds per run (I didn't run the full map, just until the 2 frogs next to the chest). For the sake of being broad, we'll round it off to 30 seconds. I have the fish thing from the Kimono that increases my item rate by 3%, Hattori Hanzo which is another 15%, and I'm a "premium member" which gives me +20 I believe. I'm not sure if 20 is a percentage, so let's just negate that and all of my other boosts, and stick with the steal attack. We'll also negate the login boost bonus for this.
Luckily I've always been a twin sword user, so I happen to have Steal attacks sitting around in my inventory. I evolved it to rank 3 giving me a 1.8x drop rate. I've also read that drops may be about 1 in every 20 runs, or 5%. I don't know the exact drop rate, but we'll use that as our initial drop rate. If you know the actual rate, then feel free to plug it in yourself. Or maybe this game is just that big of an RNG fest.
So with all that taken into account, let's get started. 11 hours, or 660 minutes, with eleven 10 minute breaks makes my total play time 550 minutes. Really simple. Now given 30 seconds per run, that's 2 runs per minute. With my 550 minute gaming time x2, that's a total of 1,100 runs. Now let's imagine I magically obtained an orange marble at the end of my last run. 1/1,100 gives us 9.091x10^-4, or .091%. Given the original ratio versus my given percentage, it comes out to about 54.9451, or 5,494.51% difference. But wait, there's still the factor of me getting the orange marble out of all the other marbles that COULD have dropped. Which according to the link I gave above, is 21. That means, I have a 1 in 21, in a 1/1,100 chance of getting an orange marble which comes out to 4.33x10^-5, or .0000433%. THAT means that the average player without steal attack 3 has a 2.405x10^-5 chance, or a .0000241% chance.
Even without taking into effect my title, fish, and membership thingy, the chances of getting an orange marble as an average player is literally mathematically improbable. It's a 2.45...................OUT OF 1 MILLION percent chance to get an orange marble. If you live in the U.S, those are about the same odds as you getting hit by a Tsunami.
Now before everyone goes crazy posting on how they got 1, or "claiming" they have 8 and I'm just a loser, this is all theoretical. What are the odds, really, that I was just unfortunate for the duration of the time? That would take awhile to calculate. But other people were doing the same thing, with the SAME results. I NEVER ACTUALLY GOT THE MARBLE as stated above. Or any for that matter. This was just during my play time. What are the odds I would have gotten the marble next run? Or in 100? According to this, I would just have to do this about 9 more times, and I would be guaranteed one, assuming several things that is. The only good thing is my steal attack is now max level.
*SIGH*