In article , Matty F wrote:
So I made a chart using Excel to show all of the 64ths of an inch as 4
decimal digits. That shows 1/32" as 0.0313" because Excel has rounded
up from 0.03125", correctly I believe.
The British and US engineering tables show 1/32" as 0.0312", so they
have truncated instead of rounding. And many other figures are
truncated as well.
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect Excel
has an option for it somewhere if you want to make your chart match).
http://en.wikipedia.org/wiki/Roundin...d_half_to_even

On Sep 20, 8:12 pm, (Alan Braggins) wrote:
In article , Matty F wrote:
So I made a chart using Excel to show all of the 64ths of an inch as 4
decimal digits. That shows 1/32" as 0.0313" because Excel has rounded
up from 0.03125", correctly I believe.
The British and US engineering tables show 1/32" as 0.0312", so they
have truncated instead of rounding. And many other figures are
truncated as well.
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect Excel
has an option for it somewhere if you want to make your chart match).http://en.wikipedia.org/wiki/Roundin...d_half_to_even

The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

On Tue, 20 Sep 2011 09:30:41 +0100, Matty F wrote:

On Sep 20, 8:12 pm, (Alan Braggins) wrote:
In article
,
Matty F wrote:
So I made a chart using Excel to show all of the 64ths of an inch as 4
decimal digits. That shows 1/32" as 0.0313" because Excel has rounded
up from 0.03125", correctly I believe.
The British and US engineering tables show 1/32" as 0.0312", so they
have truncated instead of rounding. And many other figures are
truncated as well.
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect Excel
has an option for it somewhere if you want to make your chart
match).http://en.wikipedia.org/wiki/Roundin...d_half_to_even

The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that round
up.

As I see it, it is the issue of always rounding the mid-point value (i.e.
5) in a specific direction that is a cause of bias. Hence the other
approaches that attempt to balance that out. Effectively the sum of all
values rises due to your always rounding up 5.

--
Rod

On Sep 20, 9:00 pm, polygonum wrote:
On Tue, 20 Sep 2011 09:30:41 +0100, Matty F wrote:
On Sep 20, 8:12 pm, (Alan Braggins) wrote:
In article
,
Matty F wrote:
So I made a chart using Excel to show all of the 64ths of an inch as 4
decimal digits. That shows 1/32" as 0.0313" because Excel has rounded
up from 0.03125", correctly I believe.
The British and US engineering tables show 1/32" as 0.0312", so they
have truncated instead of rounding. And many other figures are
truncated as well.
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect Excel
has an option for it somewhere if you want to make your chart
match).http://en.wikipedia.org/wiki/Roundin...d_half_to_even

The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that round
up.

As I see it, it is the issue of always rounding the mid-point value (i.e.
5) in a specific direction that is a cause of bias. Hence the other
approaches that attempt to balance that out. Effectively the sum of all
values rises due to your always rounding up 5.

But the tables in the engineering handbooks appear to truncate, which
is far less accurate.

On Tue, 20 Sep 2011 10:41:23 +0100, Matty F wrote:

On Sep 20, 9:00 pm, polygonum wrote:
On Tue, 20 Sep 2011 09:30:41 +0100, Matty F
wrote:
On Sep 20, 8:12 pm, (Alan Braggins) wrote:
In article
,
Matty F wrote:
So I made a chart using Excel to show all of the 64ths of an inch
as 4
decimal digits. That shows 1/32" as 0.0313" because Excel has
rounded
up from 0.03125", correctly I believe.
The British and US engineering tables show 1/32" as 0.0312", so they
have truncated instead of rounding. And many other figures are
truncated as well.
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other
numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect
Excel
has an option for it somewhere if you want to make your chart
match).http://en.wikipedia.org/wiki/Roundin...d_half_to_even

The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that
round
up.

As I see it, it is the issue of always rounding the mid-point value
(i.e.
5) in a specific direction that is a cause of bias. Hence the other
approaches that attempt to balance that out. Effectively the sum of all
values rises due to your always rounding up 5.

But the tables in the engineering handbooks appear to truncate, which
is far less accurate.

You always have to remember that Excel is for bean-counters so total sums
are important to them.

But if you are measuring engineering things, you might as well round down.
So long as there is sufficient precision for the purpose, whatever that
may be, things are often slightly smaller due to wear.

And you can control the rounding pretty much to your heart's content if
you put the effort in to using the appropriate functions, etc. If you care
enough, then never rely on the display precision mechanism - actually
choose what you want done.

--
Rod

In article , Tim Streater wrote:
(Alan Braggins) wrote:

In article
, Matty F
wrote:
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect Excel
has an option for it somewhere if you want to make your chart match).
http://en.wikipedia.org/wiki/Roundin...d_half_to_even

This is surely only important if you're gonna compute with the rounded
numbers. AIUI, Matty is just going to display them. And surely also
Excel has the "true" value [1] internally anyway, so ISTM that if you
did add them in Excel, you'd get an unbiassed result.

Yes, but if he wants to display them matching the official charts,
he'll have to display them using the same rounding method that the
official charts do. He already realises that he's displaying them to
a precision that he can't measure to and therefore that it doesn't
really matter.

On 20/09/2011 10:41, Matty F wrote:

So I made a chart using Excel to show all of the 64ths of an inch as 4
decimal digits. That shows 1/32" as 0.0313" because Excel has rounded
up from 0.03125", correctly I believe.

That is the convention I was taught mumble mumble years ago but
approximating by rounding down is no less accurate than rounding up.

The British and US engineering tables show 1/32" as 0.0312", so they
have truncated instead of rounding. And many other figures are
truncated as well.

snip

But the tables in the engineering handbooks appear to truncate, which
is far less accurate.

There can be a difference between truncation and rounding down. The
example given above could equally be rounded down rather than truncated.
So how would the engineering tables you refer to treat 3/64ths - 0.046875?

--
Roger Chapman

"Alan Braggins" wrote in message
...
In article , Tim
Streater wrote:
(Alan Braggins) wrote:

In article
,
Matty F
wrote:
I realise that the measurements will be less accurate than 0.00005"
but that's not the point. My chart is different from the official
charts that were probably calculated with a slide rule or an abacus
100 years ago. Isn't it accepted these days to round upwards and not
truncate?

There's no one generally accepted rule. Can you tell from other numbers
in the chart whether they are rounding down, or rounding to even?
The latter avoids systematic bias, and is fairly common (I expect Excel
has an option for it somewhere if you want to make your chart match).
http://en.wikipedia.org/wiki/Roundin...d_half_to_even

This is surely only important if you're gonna compute with the rounded
numbers. AIUI, Matty is just going to display them. And surely also
Excel has the "true" value [1] internally anyway, so ISTM that if you
did add them in Excel, you'd get an unbiassed result.

Yes, but if he wants to display them matching the official charts,
he'll have to display them using the same rounding method that the
official charts do. He already realises that he's displaying them to
a precision that he can't measure to and therefore that it doesn't
really matter.

Any errors caused by rounding should be covered by the tolerance being
worked to.
So there will be a range of over and undersized values that will be 1/32.
I don't see why there should be an issue, all that is needed is a table that
lists the fraction and the allowable range.
That range may need to be different for pins and for holes to ensure they
fit.

On 20/09/2011 10:00, polygonum wrote:
The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that
round up.

Four digits, 0, 1, 2, 3 and 4.

'nuff said!

Andy

On Tue, 20 Sep 2011 18:57:07 +0100, Andy Champ
wrote:

On 20/09/2011 10:00, polygonum wrote:
The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that
round up.

Four digits, 0, 1, 2, 3 and 4.

'nuff said!

Andy

The zero doesn't need to be rounded, does it?

--
Rod

On 20/09/2011 18:57, Andy Champ wrote:
On 20/09/2011 10:00, polygonum wrote:
The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that
round up.

Four digits, 0, 1, 2, 3 and 4.

'nuff said!

Weird innit. But he's right. Look at the sum of 0.1-10.0 in steps of 0.1
- 505. Now round to integer, always rounding the 0.5 up - ans = 510 -
it's a bit high. Now try banker's rounding, ie if it's x.5, round to the
even number. 0.5 - 0, 1.5 - 2, etc. Sum = 505, ie no systematic bias.

On Sep 20, 7:13*pm, Clive George wrote:
On 20/09/2011 18:57, Andy Champ wrote:

On 20/09/2011 10:00, polygonum wrote:
The top Google result for imperial fraction conversion rounds the way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9 rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that
round up.

Four digits, 0, 1, 2, 3 and 4.

'nuff said!

Weird innit. But he's right. Look at the sum of 0.1-10.0 in steps of 0.1
- 505. Now round to integer, always rounding the 0.5 up - ans = 510 -
it's a bit high. Now try banker's rounding, ie if it's x.5, round to the
even number. 0.5 - 0, 1.5 - 2, etc. Sum = 505, ie no systematic bias.

I have occasionally wondered if Benfor'ds law has anything to do with
this...

http://en.wikipedia.org/wiki/Benford%27s_law

Jon N

On Wed, 21 Sep 2011 15:14:49 +0100, jkn wrote:

On Sep 20, 7:13 pm, Clive George wrote:
On 20/09/2011 18:57, Andy Champ wrote:

On 20/09/2011 10:00, polygonum wrote:
The top Google result for imperial fraction conversion rounds the
way
that I say is correct, i.e. 0 1 2 3 4 rounds down and 5 6 7 8 9
rounds
up. Where is the systematic bias in that?

http://www.hamuniverse.com/antfrac.html

? That means there are four digits that round down against five that
round up.

Four digits, 0, 1, 2, 3 and 4.

'nuff said!

Weird innit. But he's right. Look at the sum of 0.1-10.0 in steps of 0.1
- 505. Now round to integer, always rounding the 0.5 up - ans = 510 -
it's a bit high. Now try banker's rounding, ie if it's x.5, round to the
even number. 0.5 - 0, 1.5 - 2, etc. Sum = 505, ie no systematic bias.

I have occasionally wondered if Benfor'ds law has anything to do with
this...

http://en.wikipedia.org/wiki/Benford%27s_law

Jon N

I notice that link mentions the law being extended for other number bases.
Binary anyone? :-)

--
Rod

On Sep 22, 2:14 am, jkn wrote:

I have occasionally wondered if Benfor'ds law has anything to do with
this...

http://en.wikipedia.org/wiki/Benford%27s_law

I assume that Benford's Law applies to house numbers.
For a long time I have noticed that shops selling the numbers that you
put by your gate often have the numbers 1,2, 3 missing, which are the
precise numbers that I have needed for my last two houses. And all
shops seem to order the wrong quantities of numbers
This is because the numbers 1, 2, 3 actually occur more often in
streets that have a few hundred houses in them.

I even worked out the ratios needed:
1 22
2 16
3 13
4 9
5 8
6 7
7 7
8 6
9 6
0 6

It's because in the physical universe of human measurements there's no
such thing as 0.5
You either have 0.50000000000000000000023489701 or something similar
or 0.4999999999999999999999993462654 or something similar.
So, of course, 0.5(whatever) rounds up and 0.4(whatever) rounds down.

JGH

On Sep 20, 1:44*pm, polygonum wrote:
....
So long as there is sufficient precision for the purpose, whatever that *
may be, things are often slightly smaller due to wear.

Holes aren't.

"dave" wrote in message
...
On Sun, 25 Sep 2011 03:45:56 -0700 (PDT), hognoxious
wrote:

On Sep 20, 1:44 pm, polygonum wrote:
...
So long as there is sufficient precision for the purpose, whatever that
may be, things are often slightly smaller due to wear.

Holes aren't.

Or in fact, anything travelling very quickly indeed!

If you are talking about near light speed you should note that a recent LHC
experiment may prove Einstein to be wrong.
Who said you can't change the (written) laws of physics?
Some question about the event being seen before it happened.

On Sep 26, 12:34*am, dave wrote:
On Sun, 25 Sep 2011 03:45:56 -0700 (PDT), hognoxious

wrote:
On Sep 20, 1:44 pm, polygonum wrote:
...
So long as there is sufficient precision for the purpose, whatever that
may be, things are often slightly smaller due to wear.

Holes aren't.

Or in fact, anything travelling very quickly indeed!

Actually, they will be heavier but shorter (in the direction of
travel).

.... and ignore any assertions that Relativity has been overturned: a)
The scientists are almost certain they have made a mistake; b) even if
Relativity is wrong, we know from experiment that fast moving objects
are heavier, and I'm pretty sure we know they are shorter too.

On 26/09/11 14:22, Martin Bonner wrote:


... and ignore any assertions that Relativity has been overturned: a)
The scientists are almost certain they have made a mistake; b) even if
Relativity is wrong, we know from experiment that fast moving objects
are heavier, and I'm pretty sure we know they are shorter too.

It will never be wrong, just possibly necessary in some very specialised
case to use a more accurate theory.


--
djc

On Mon, 26 Sep 2011 06:22:19 -0700 (PDT), Martin Bonner
wrote:

b) even if
Relativity is wrong, we know from experiment that fast moving objects
are heavier, and I'm pretty sure we know they are shorter too.

I don't know of many short, fat sprinters.