Weekly network forecast 7th January 2013

0.Introduction

If you're happy with < 10% error in your forecasts, this week's errors were acceptably useful. Since (barring the changes due to the reward halving) accuracy has been generally good,  it's possible to use the weekly hashrate forecasts to estimate the date of a retarget and a forecast estimate for the retarget difficulty.

For example based on this weeks model f1, f2, f3 and f4 weekly hashrate forecasts, we can forecast the retarget at block 217728 will be on 21st January and difficulty will change to ~ 3657934.

So this for this week I've included:

• A table of current retarget date and difficulty estimates
• A table of previous retarget date and difficulty estimates, and the actual retarget dates and difficulties as a comparison
• A chart of the last twenty six weeks of retarget date and difficulty estimates, actual retarget dates and actual difficulties.

It should be noted that each retarget will often be forecast by two consecutive weekly forecasts, hence the multiple points per retarget on the new chart. Please post a comment if it's not clear. 

1. Models and datasets:

The model datasets have been collected into one paste to save time. Model estimates have been likewise aggregated.

Forecast and canary model analysis

All datasets

All estimates

Difficulty data and estimates

2. Results

• Canary model (current hashrate estimate based only on current price and previous network hashrates): This model's error has recovered to 4% of the actual weekly average network hashrate this week. The Canary model was outside the expected range for only 3 weeks after the reward halving, so it seems to remain a good indicator of the onset of changes other than the MTGOX BTCUSD price and previous network hashrate averages.
• Model.f1 (one week forecast): Model.f1's error recovered to 5% of the weekly average network hashrate, almost as low an average error as in the weeks leading up to the reward halving. Hopefully the model will remain useful until the ASIC hashrates are added.
• Models f2, f3 and f4 errors are high, and although within the estimated 95% confidence interval for the error are not yet useful for long range forecasts.
• The large negative difficulty change after the block reward halving was (of course) not predicted and stands out as a clear error. However the new estimates look on target, and I think an estimate of Difficulty ~ 3.6 million after the next retarget is reasonable.

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Thanks to the following for use of their data:

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blockchain.info

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