Time to derailment miscalculated?

Hi there!
Sorry if this has been answered before - I did make an effort to find it in the FAQs and forum.
I have a goal with 6 hours due per week. I worked 3 hours and entered it in, and the time till derailment went from 8 days 6:29 and change to 10 days 6:29 and change, which is only 2 days. But 3 hours is half my weekly quota, so I think it should add 3 1/2 days to the time till derailment. This has happened to me before as well. There are also times when it adds too much time till derailment. Is this some kind of rounding thing?
Thanks in advance for your help!!

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Hi Amy!

Ah, sounds like this was partly a confusion about how the deadlines work! Your deadline is always at the same time, so it isn’t possible to add 0.5 days of buffer: it will always be a whole number. So I think that accounts for the “rounding error” you’re seeing.

It’s not that you lose credit for units entered, though! You can also see how much is due at your next deadline, and that number will have changed too. E.g. with this goal of mine:

The daily rate for this goal is 121, but I only need to add +46 right now. If I add a datapoint of +64, now the header looks like this:

I’ve gained a whole 24 hours of buffer even though I only added +64. In addition, the extra I’ve done has been taken off the next deadline’s required amount (I only needed to add 46, but I added 18 more units than I needed, and then 121-18=103).

The other thing to note is that weekly goals don’t really work any differently than daily goals, so by having a goal of 6/week, you essentially have a daily goal with a rate of 6/7 per day, or 0.857142857. Each time you add +0.857142857, you gain a day of buffer. I’ll bet that’s what happening is that as you’re adding data, you aren’t always adding exact multiples of 0.857142857, so you’re gaining more or less than a day’s worth of units… and since deadlines only happen once per day rather than continuously, that accounts for what you’re seeing as rounding issues.

Does that help a bit?

Hi Shanaqui,
Thank you very much for your detailed reply. I appreciate it very much.

I have learned a lot from your reply. However, I guess I’m still a bit confused.

Actually, although the rate is shown as 6hr/week(which i changed to recently), I suspect that it is still using 12 hours per week as my goal. This is because in Take a Break/Upcoming Changes it says:

Through 2028-10-27 increase at rate 12

Through 2031-05-25 increase at rate 12

Through 2031-05-29 increase at rate 12

Through 2031-05-29 increase at rate 6

So maybe I accidentally put in my change to 6 hours per week to start in 2031? Why then does the rate show as 6 hours per week under the graph?

If you think that the rate is still 12 hrs per week, there is no need to read further - that would be the problem!

But if that is not the problem, I have tried to explain below why I am still a bit confused. I hope it’s clear and not too boring/exhausting!!

So just to recap, my goal is 6 hours per week. From your reply, I understand that each time I complete 6/7 of an hour I should gain a day of buffer. I have completed and entered 3 hours of work on the 25th, which is more than 3 times my daily requirement. However, time to derailment was only increased by 2 days.

I think that you are saying that, if you have entered a remainder amount (i.e. some fraction of your daily requirement - less than 6/7 of an hour), the amount due on derailment day is reduced by that number, so time to derailment is actually increased although the derailment date is the same, because there is less work to do on derailment day.

Is this correct: Three hours of work is 3x6/7 (3 daily requirements) plus a remainder of 3x1/7, so 3/7 hours (over 25 minutes) should be subtracted from what is due on derailment day, and 3 whole days should be added to the derailment date.

On the derailment date, 41 minutes is currently due. I would expect it to be, at most, 6/7 hours(daily requirement) minus the 3/7 fraction I entered, which is approximately 51 minutes - 25 minutes or something around 26 minutes more or less. I don’t understand how it could be 41 minutes, unless the amount due on derailment day can go above the daily requirement.

Thank you again for all your help!!

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Hi Amy!

Sounds like you changed your rate to 6 hours (that’s why that shows as your commitment)… but anything you’ve pre-set in the graphs (e.g. breaks, future rate changes, etc) doesn’t get edited, and that’s still set to the original 12 hours. I’m not quite sure how you’d have ended up with things set up quite like that – it might be worth emailing us at support so we can try to understand it better, so we can maybe make things clearer in future? Or if you remember what you’ve done to the goal in the past, it’d be really helpful to understand how that confusion came about! (Or even potential bugginess.)

The easiest way for you to change the graph now is probably using the visual graph editor: graph.beeminder.com

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Thank you again for all of your help, Shanaqui. I greatly appreciate it.
I will email support about my rate and see if I can remedy that!
Thanks again,