Since Constant Block Reward (CBR) has been introduced, average staking difficulty stabilized around 8 - this is what we get from averaging data published in the blockchain. I was interested how close real life staking frequency is.

Staking is highly probabilistic, we can only expect some events to happen, but there is no certainty. Small sample leads to huge variance and easily leads to wrong conclusions. As my balance is small, only a bit over 20k, I have found two addresses that seem to be online continuously - and fetched data from block explorer. All three have UTXOs of max 8k, usually even smaller, i.e. are quite well optimized for staking. All three had little to no downtime. Below smaple is still on the smallish side for analysis purposes.

- Nov - about 3 weeks of November after CBR was introduced
- Dec - full month
- Jan - first 11 days of January, as today is only 12th

 B - wallet-address balance, S - number of staked blocks.

B | S - Nov | Nov EDIFF |  S - Dec | Dec EDIFF |  S - Jan | Jan EDIFF
 ------------- | ------------- | ------------- | ------------- | ------------- | ------------- | -------------
460 000 | 146 | 7.3 |  147 | 9.3 |  51 | 9.5 | 
120 000| 39 | 7.1 |  35 | 10.2 |  12 | 10.6 | 
27000 | 5 |9.2 |  2 | 37.2 | 4 | 9.2 | 

Note: the smallest balance in Nov - 21k, in Dec - 25k, in Jan - 35k. 

Balance of 480k had easiest time to stake, although difference  over 120k is small. Littile balance of ~ 25k had hard time in December. In fact wallet managed to find 4 blocks, not 2, but strange error happened and chain was immediately reorganized and 2 stakes not recognized by network.

- Network difficulty experienced by wallets seems about 10 to 30 per cent higher than value calculated and  published in [Gridcoin - State of the Network](https://steemit.com/gridcoin/@parejan/gridcoin-state-of-the-network-7-january-2018).
- Wallet with balance of ~100 000 should stake quite regularly, daily, but you can still got caught by black witch of probability
- From the wallet with balance of ~30 000 you cannot expect regular staking, you might go a full month without staking once due to natural variance

# EDIFF

Oh, you may wonder how *experimental difficulty* was calculated. The following relation should be true:

- S/TB = B/N

where S - number of staked blocks, TB - total number of blocks in the period, B - wallet-address balance, N - total coins in the network. Thus:

- EDIFF = N / 10 000 000 = B * TB / ( S * 10 000 000)