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DataPacRat comments on Thinking Bayesianically, with Lojban - Less Wrong Discussion

11 Post author: DataPacRat 24 January 2012 06:47PM

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Comment author: DataPacRat 24 January 2012 09:40:40PM 1 point [-]

So "ju'u re pi no pa" is 1/4?

Exactly so.

0 -> 1:1, 50% 1 -> 2:1, 67%

To see if I understand this correctly; then in this approach, each increase of 1 bit is equivalent to an increase of 3 decibels?

0 dbs -> 1:1 -> 0 bits 3 dbs -> 2:1 -> 1 bit 6 dbs -> 4:1 -> 2 bits 9 dbs -> 8:1 -> 3 bits 12 dbs -> 16:1 -> 4 bits 15 dbs -> 32:1 -> 5 bits 18 dbs -> 64:1 -> 6 bits

(For precise numbers for the decibels, I use the formula: decibels = 10 * log(10) (LevelOfBelief / (1 - LevelOfBelief)) . So to check how many decibels are equivalent to 64:1 odds, I plug into Google Calculator: 10 * log ((64/65) / (1/65)) , getting 18 and change.)

Comment author: [deleted] 24 January 2012 09:45:27PM *  1 point [-]

each increase of 1 bit is equivalent to an increase of 3 decibels?

approximately. because 3 bits is a factor of 8 which is approximately 10, and 3 decibels is approximately one third of the way to 10.

Comment author: DataPacRat 24 January 2012 10:30:42PM 1 point [-]

Okay, so we don't actually have to change the base we're counting in, we'd be changing the units we're counting - instead of X number of decibels, it would be X number of bits, and X can be expressed in base 10 either way.

I'd like to take a day or so to think about the best way to approach this - it may very well be as simple as adding a note to the reftext about how to convert decibels to bits by dividing by three.

Comment author: [deleted] 24 January 2012 10:44:59PM *  1 point [-]

Yeah, number of bits is still expressed in base ten (lol, I just realized that all bases are base 10 in their own base).

I don't know about this divide by three business. it's not exactly 3. You should use the correct value.

EDIT: log(10)/log(2) = 3.3219

Comment author: thomblake 25 January 2012 08:05:14PM *  1 point [-]

It seems like divide by 3 should be about right. 2**10 is roughly 10**3, so 30 decibels is about 10 bits. (1024 versus 1000).

Comment author: [deleted] 25 January 2012 08:40:15PM 1 point [-]
log10(1024) = 3.010
10/3.010 = 3.32

You are right, the conversion factor is 3.01.

Comment author: DataPacRat 25 January 2012 09:03:03PM 0 points [-]

I've tried to take the 'outside view' on this, to see if I'd originally come up with the idea of using bits, whether it would be worth switching to decibels. Using decibels, only two digits brings you all the way to the billions-to-one level of odds, which seems sufficient for everyday purposes; and decibels dividing probability-space more finely allows for easy differentiation between some useful probability numbers, such as 'beyond a reasonable doubt' and 'clear and convincing evidence', which would be blurred if using bits.

So I think that I'm going to keep bei'e as being measured in decibels, add a note to the definition about conversion to bits... and, I think, add a note that anyone who really wants to have an experimental cmavo that uses bits is as free to create and use it as I was to create bei'e. Sound good to you?

Comment author: [deleted] 25 January 2012 09:24:18PM 1 point [-]

sure why not.

I just find bits more natural. People talk about twice as much (+1 bit) often, and bits are the unit used in information theory and computer science.