Understanding Shares in Pool Mining I just started mining today at Dogechain pool. I wanted to see what mining was like, so I'm only using minerd with my CPU. I don't expect a lot until I get a GPU rig going, but something doesn't seem right. 

For instance, I'm averaging 8-10 kH/s hashing rate (sometimes as high as 15, sometimes as low as 5). On minerd, after about 6 hours I'm over 200/200 accepted, but on Dogechain pool, I've only earned 21 Dogecoin. During the last block round, my shares went over a 100, and in the pool stats, it shows my hashrate as averaging between 225 and 250 doge/day. At this rate, I'll only be earning about 80 a day. According to coinwarz at 8 kH/s, I should at least be earning 108 a day.

It seems like the rate of reward is really low, even for CPU mining. Can anyone give me an idea why?
The income you earn will vary from what you would expect to earn on a given day.  In order to earn income a block must be found and until a block is found you will earn nothing.  For example, let's assume your pool on average founds a block every 2.5 hours and each block you earn 11.25 doge.  You would have earned about 22.50 doge in the timeframe of 6 hours.  In the first 24 hours,  you would earn about 101.25 doge.  The next day you would earn about 112.50 and the next day would be 101.25 doge, but your daily average over 5 days is 108 doge.  

Of course, in reality you would never see blocks found with such regularity.  Instead, you might find only 7 blocks on day one and then 13 blocks on day 2 and so on.  Blocks are found randomly and so you can expect your income to be all over the place.  Overtime, you will see your average income reflect your expected income with a lower variance depending how many days you factor in.

So far, you have no basis to be concerned and it seems your low income is just example of bad luck, but over time luck becomes a lesser factor.  You should get to 108 a day and on some days you will earn more.  Happy mining :).