How
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
The Bureau of Labor Statistics publishes its weightings, its data, and its methodology. Anybody who wants to can read, calculate, and criticize them.grayfox wrote: ↑Mon Apr 16, 2018 4:57 pm ...
I compared inflation from BPP with inflation from CPI-U. Someone said both use the same basket and weights, and only difference is the method of sampling prices. And yet sometimes they differed by as much as +/-1.5%. Include standard errors and it is probably only good to +/-2%. <--This is what I am concluding.
Considering that the we're trying to measure a 2% rate, that is huge measurement error. When BLS reports 2%, I bet true 12-month inflation could be anywhere from 0 to 4%.
If that's the case, I think its a huge problem. E.g. GDP. If Nominal GDP growth is 4.1% p.a., what is real GDP growth if annual inflation is 2.4% +/- 2%. We could be in a recession and not know it. The instruments don't work well in real time.
What do you expect CPI to measure?
PJW
Last edited by Phineas J. Whoopee on Mon Apr 16, 2018 5:34 pm, edited 1 time in total.
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
If you disagree with the BLS's weightings, data, or methodology, all that's fine and it's published.
If you live, for example, in Juneau AK, the price of wild-caught Pacific salmon might be, I'm making up unrealistic examples, $1.00 per pound. If in Atlanta GA it costs $2.00 per pound, what are consumer prices?
PJW
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
You did not say you disagree, you said you think there is uncertainty. You began with asking about calculations to three decimal places. You're absolutely correct to ask that.
If I understand properly you're questioning the relationship of reported CPI to reported GDP. Yes indeed, they both have uncertainties.
Suggesting we don't know what inflation is, when we do know what CPI-U is because it's tightly defined and all the information published, is incorrect. We do know what CPI-U is. If you mean we don't know with precision (not accuracy) what it implies, you are correct. If you're saying inflation is a poorly-defined term you're correct about that too.
In between somebody suggested CPI, in general across the nation across the economy average of everywhere is incorrect because it doesn't match their own personal expenses as they change year to year. That's not right. It isn't even wrong. That's not what CPI measures.
Inflation, regardless of how many decimal places CPI is reported to, is imprecise. You asked whether it's accurate. Those are two different things.
PJW
- whodidntante
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Re: How accurately can we measure INFLATION?
Horseshoes and wagon wheels are entirely overpriced in 2018!
Re: How accurately can we measure INFLATION?
I don’t understand what you are trying to say here:”Sure you can sample prices and get the current prices. But prices are changing all the time.”grayfox wrote: ↑Mon Apr 16, 2018 4:57 pm I think that measuring inflation is not so simple. You have prices and CPI-U which are levels. We want to know inflation which is a rate of change over time. It means taking differences, a.k.a derivatives, which are noisy.
Sure you can sample prices and get the current prices. But prices are changing all the time.
I just bought strawberries at the supermarket. 2 lbs for $5.00. The supermarket has a weekly flyer with the new prices. Last week strawberries were $3.99/lb. In the winter they were $4.99 some weeks. In the summer they get as low as $1.99/lb. It all depends on how plentiful they are. They cut the price by 50% to move them. So the prices can change by 25% or 50+% week to week.
Then you try to find the inflation trend on the order of 2% in prices that are changing 10-50% every week.
The short term fluctuations dominate in the short term. Monthly inflation is probably just measuring noise. You need longer periods of time to observe a trend. Even a year is a short time.
I compared inflation from BPP with inflation from CPI-U. Someone said both use the same basket and weights, and only difference is the method of sampling prices. And yet sometimes they differed by as much as +/-1.5%. Include standard errors and it is probably only good to +/-2%. <--This is what I am concluding.
Considering that the we're trying to measure a 2% rate, that is huge measurement error. When BLS reports 2%, I bet true 12-month inflation could be anywhere from 0 to 4%.
If that's the case, I think its a huge problem. E.g. GDP. If Nominal GDP growth is 4.1% p.a., what is real GDP growth if annual inflation is 2.4% +/- 2%. We could be in a recession and not know it. The instruments don't work well in real time.
That is exactly what the CPI measures — changes in prices. The CPI is not a “level.” It is an index that, by definition, measures the rate of change between two time periods.
Also, seasonal changes in prices that occur on a consistent basis are adjusted for in the CPI: https://www.bls.gov/cpi/seasonal-adjust ... nswers.htm
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
Re: How accurately can we measure INFLATION?
One way for sure that the CPI can be improved is by sampling more items and their prices. Larger samples mean smaller sampling errors, all other things being equal.
So if you want a better CPI, lobby your congressperson to increase its budget.
So if you want a better CPI, lobby your congressperson to increase its budget.
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
- triceratop
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Re: How accurately can we measure INFLATION?
This may be of some interest, so I'll pass it along: The Index Number Problem: A Differential Geometric Approach. [pdf]adam1712 wrote: ↑Mon Apr 16, 2018 2:06 pmThe CPI does try to remove some of the effects of the change in value of items in the basket of goods by reweighting the basket based on substitution effects and adding/removing items over time. Many economists however think there is still some effect from the change in value of items and CPI overstates inflation that is purely from the decline in the value of the dollar.Oicuryy wrote: ↑Mon Apr 16, 2018 11:53 am The Consumer Price Index (CPI) does not measure inflation. It measures the change in the price of a basket of consumer goods and services.
The price of a thing, in dollars, is the ratio of the value of the thing to the value of a dollar. A price of five dollars for some thing means the value of the thing is five times the value of a dollar. A price could increase because the value of the thing went up and/or because the value of a dollar went down.
Axiom 1 implies that inflation is a decline in the value of a dollar. The trick to measuring inflation is to figure out how much of a change in prices is due to a change in the value of things and how much is due to a decline in the value of a dollar.
Ron
Simply from a mathematical perspective it's a fascinating result.Pia Malaney Thesis: Abstract wrote:The first part of this thesis looks at issues in index number theory. By
using techniques developed in differential geometry, it is shown that the so-
called index number problem can be resolved by the development of a special
economic derivative operator constructed for this purpose. This derivative
is shown to give rise to a unique differential geometric index number which
is then demonstrated to equal the Divisia index. It is then shown in the
second chapter (co-authored with Eric Weinstein) that when placed under
similar assumptions, this data based index equals the Konus index, previously
asserted to be incalculable in the absence of a knowledge of preference maps.
"To play the stock market is to play musical chairs under the chord progression of a bid-ask spread."
Re: How accurately can we measure INFLATION?
An index is set to 100.0 in its base period, which is a particular point in time. If the index equals 104.0 at one year after the base period, then prices have gone up 4% in one year. That is all you can say based on those two numbers — 100.0 and 104.0.
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
Re: How accurately can we measure INFLATION?
In my mind the biggest thing left out of most inflation figures is the cost of healthcare.
Healthcare costs seem to go up more than any of the inflation indexes.
And the older you get, the more likely you are to need healthcare
Healthcare costs seem to go up more than any of the inflation indexes.
And the older you get, the more likely you are to need healthcare
Retired 2019. So far, so good. I want to wake up every morning. But I want to die in my sleep. Just another conundrum. I think the solution might be afternoon naps ;)
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
Healthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
Re: How accurately can we measure INFLATION?
I don't think I'm explaining myself clearly. I'm saying the inflation that matters is the change in value of the things you buy, not the change in your personal budget.Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 4:18 pmIndividual expenditures is not what CPI means at all.PVW wrote: ↑Mon Apr 16, 2018 3:55 pm ...
The Bureau of Labor Statistics has not started reporting the CPI-PVW, but my only concern about the BLS measures of inflation are how they affect my government benefits.
There is a CPI-PVW and CPI-Phineas J. Whoopee. In figuring my expenditures, I only care what CPI-PVW is. Maybe your point is that I can't calculate CPI-PVW, and I agree, but that doens't change the fact that your personal inflation rate is the only one that matters for your expenses.
If I like collecting vintage sports cars, and the price of vintage sports cars goes up, that's inflation.
If I stop spending money on vintage sports cars and start spending on cardiac care, stents for example, that is not inflation.
Inflation is one thing. Personal expenses are another.
PJW
If you are investing your money to eventually purchase a 1932 Packard Eight Phaeton, then the change in price of that car is the only thing that matters. It doesn't matter that last year you didn't buy a vehicle. It doesn't matter what the average price index for pre war Packards is. The only thing that matters is the inflation of the things you buy.
Re: How accurately can we measure INFLATION?
I'll admit I did not read the whole list. Does the SS inflation adjutment at least keep up with the medicare premiums (and copays)?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
Retired 2019. So far, so good. I want to wake up every morning. But I want to die in my sleep. Just another conundrum. I think the solution might be afternoon naps ;)
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
Good. We agree. Inflation is a macroeconomic measure. It can inform one's personal choices, but it isn't designed to, and does not, give an indication about what one personally will spend.PVW wrote: ↑Mon Apr 16, 2018 7:58 pm ...
I don't think I'm explaining myself clearly. I'm saying the inflation that matters is the change in value of the things you buy, not the change in your personal budget.
If you are investing your money to eventually purchase a 1932 Packard Eight Phaeton, then the change in price of that car is the only thing that matters. It doesn't matter that last year you didn't buy a vehicle. It doesn't matter what the average price index for pre war Packards is. The only thing that matters is the inflation of the things you buy.
I am not aiming these links at you individually, PVW. I include them for anybody else who may come across this thread.
Macroeconomics
Microeconomics
PJW
Re: How accurately can we measure INFLATION?
Medicare premiums are prevented by law from increasing faster than Social Security payments for existing recipients.dknightd wrote: ↑Mon Apr 16, 2018 8:04 pmI'll admit I did not read the whole list. Does the SS inflation adjutment at least keep up with the medicare premiums (and copays)?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
So if your copays go up 10%, then you think the SS inflation adjustment should go up 10%?
What if the cost of your groceries goes up 5%; should your SS benefit go up 5%? Food is as much of a necessity as medical care.
Rhetorical questions obviously. Any inflation adjustment for SS will reflect an average change in prices across a variety of goods and services.
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
I suggest you read about the Medicare Hold Harmless Provision.
Beyond that I don't know enough about your personal situation, nor about every state, nor about Medicare supplemental plans, nor about Medicare Advantage, to go into more detail.
Nobody is insulated from all risk, financial or otherwise.
PJW
Re: How accurately can we measure INFLATION?
I think SS should cover the increase in medical costs, AND, the costs of a basket of food. As near as I can tell (not retired yet) it does not do that. I think it should.delamer wrote: ↑Mon Apr 16, 2018 8:18 pmMedicare premiums are prevented by law from increasing faster than Social Security payments for existing recipients.dknightd wrote: ↑Mon Apr 16, 2018 8:04 pmI'll admit I did not read the whole list. Does the SS inflation adjustment at least keep up with the medicare premiums (and copays)?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
So if your copays go up 10%, then you think the SS inflation adjustment should go up 10%?
What if the cost of your groceries goes up 5%; should your SS benefit go up 5%? Food is as much of a necessity as medical care.
Rhetorical questions obviously. Any inflation adjustment for SS will reflect an average change in prices across a variety of goods and services.
Otherwise I can't count on it as an inflation adjusted income.
Retired 2019. So far, so good. I want to wake up every morning. But I want to die in my sleep. Just another conundrum. I think the solution might be afternoon naps ;)
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
Don't count on it. Don't think it should.
Congress decides.
Vote.
PJW
Re: How accurately can we measure INFLATION?
Again, an increase in costs is not the same as an increase inflation. If the pill that I take once a month goes from $5 per pill to $5.50 per pill, that is a 10% inflation increase. But if I now have to take 2 pills a month, my cost just went from $5 a month to $11 a month — or 120% cost increase.dknightd wrote: ↑Mon Apr 16, 2018 8:29 pmI think SS should cover the increase in medical costs, AND, the costs of a basket of food. As near as I can tell (not retired yet) it does not do that. I think it should.delamer wrote: ↑Mon Apr 16, 2018 8:18 pmMedicare premiums are prevented by law from increasing faster than Social Security payments for existing recipients.dknightd wrote: ↑Mon Apr 16, 2018 8:04 pmI'll admit I did not read the whole list. Does the SS inflation adjustment at least keep up with the medicare premiums (and copays)?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
So if your copays go up 10%, then you think the SS inflation adjustment should go up 10%?
What if the cost of your groceries goes up 5%; should your SS benefit go up 5%? Food is as much of a necessity as medical care.
Rhetorical questions obviously. Any inflation adjustment for SS will reflect an average change in prices across a variety of goods and services.
Otherwise I can't count on it as an inflation adjusted income.
So should my SS benefit go up 10%, 120%, or something else?
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
- Phineas J. Whoopee
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Re: How accurately can we measure INFLATION?
Don't count on it. Don't think it should.
Congress decides.
Vote.
PJW
Congress decides.
Vote.
PJW
Re: How accurately can we measure INFLATION?
I guess for planning purposes I'll assume nothing, Which makes it hard to planPhineas J. Whoopee wrote: ↑Mon Apr 16, 2018 8:36 pm
Don't count on it. Don't think it should.
Congress decides.
Vote.
PJW
Retired 2019. So far, so good. I want to wake up every morning. But I want to die in my sleep. Just another conundrum. I think the solution might be afternoon naps ;)
- Phineas J. Whoopee
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- Joined: Sun Dec 18, 2011 5:18 pm
Re: How accurately can we measure INFLATION?
We don't agree. The macroeconomics definition of inflation is only useful for macroeconomists.Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 8:07 pmGood. We agree. Inflation is a macroeconomic measure. It can inform one's personal choices, but it isn't designed to, and does not, give an indication about what one personally will spend.PVW wrote: ↑Mon Apr 16, 2018 7:58 pm ...
I don't think I'm explaining myself clearly. I'm saying the inflation that matters is the change in value of the things you buy, not the change in your personal budget.
If you are investing your money to eventually purchase a 1932 Packard Eight Phaeton, then the change in price of that car is the only thing that matters. It doesn't matter that last year you didn't buy a vehicle. It doesn't matter what the average price index for pre war Packards is. The only thing that matters is the inflation of the things you buy.
I am not aiming these links at you individually, PVW. I include them for anybody else who may come across this thread.
Macroeconomics
Microeconomics
PJW
This is the one that matters,
https://www.bankrate.com/personal-finan ... tion-rate/
If you want to calculate CPI-PJW, here is a place to start
https://www.frbatlanta.org/research/inf ... mycpi.aspx
Re: How accurately can we measure INFLATION?
Money is fungible |
Abbreviations and Acronyms
- bertilak
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Re: How accurately can we measure INFLATION?
I think it all depends on how accurately (and precisely) you can define it.
May neither drought nor rain nor blizzard disturb the joy juice in your gizzard. -- Squire Omar Barker (aka S.O.B.), the Cowboy Poet
Re: How accurately can we measure INFLATION?
The standard inflation index is a triple average of a price change: it is the average change in price of the average consumption for an average family.
Therefore, it averages the price of salmon in Juneau, AK and Mobile, AL. It averages the cost of dentures and the cost of pacifiers. Since the average family, on average, buys a new vehicle every seven years, it also contains the average cost of one seventh of an average vehicle, as well as the school expenses for one thirteenth of a 14-yo child.
Many BH complain that the 3 decimals value published every month does not reflect their own perception of price changes. The inflation value is not meant to do that. They rebut that the inflation data is therefore useless.
The expected value of a single dice toss is 3.5. You better not expect that result, though; it will never come up. Not a single time over a trillion trillion tosses. Is it useless information ?
Therefore, it averages the price of salmon in Juneau, AK and Mobile, AL. It averages the cost of dentures and the cost of pacifiers. Since the average family, on average, buys a new vehicle every seven years, it also contains the average cost of one seventh of an average vehicle, as well as the school expenses for one thirteenth of a 14-yo child.
Many BH complain that the 3 decimals value published every month does not reflect their own perception of price changes. The inflation value is not meant to do that. They rebut that the inflation data is therefore useless.
The expected value of a single dice toss is 3.5. You better not expect that result, though; it will never come up. Not a single time over a trillion trillion tosses. Is it useless information ?
Re: How accurately can we measure INFLATION?
Are the price changes in each category published independently? If so, is there a tool to calculate personal inflation by changing the weights for your personal situation?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
Re: How accurately can we measure INFLATION?
Yes, indexes are published for detailed categories. I don’t know of a tool to use those to create your own inflation rate.abhikush wrote: ↑Thu Apr 19, 2018 12:51 pmAre the price changes in each category published independently? If so, is there a tool to calculate personal inflation by changing the weights for your personal situation?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
And in any case, it would be retrospective. The CPI isn’t going to tell you anything about the future.
If you wanted to breakdown your personal past cost increases into 1) inflation versus 2) changes in consumption, then it could play a role.
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
Re: How accurately can we measure INFLATION?
Yes, that is what I want to achieve i.e. get a sense of past rate of inflation using weights that are more applicable for me based on my current consumption. I will dig around the BLS website over the weekend to see what I can find.delamer wrote: ↑Thu Apr 19, 2018 1:58 pmYes, indexes are published for detailed categories. I don’t know of a tool to use those to create your own inflation rate.abhikush wrote: ↑Thu Apr 19, 2018 12:51 pmAre the price changes in each category published independently? If so, is there a tool to calculate personal inflation by changing the weights for your personal situation?Phineas J. Whoopee wrote: ↑Mon Apr 16, 2018 7:42 pmHealthcare is included in CPI. See for yourself.
You may or may not like its weighting, but it's in there.
PJW
And in any case, it would be retrospective. The CPI isn’t going to tell you anything about the future.
If you wanted to breakdown your personal past cost increases into 1) inflation versus 2) changes in consumption, then it could play a role.
Re: How accurately can we measure INFLATION?
But you don't need BLS at all! You know what you buy and how much you pay for it. At most, normalize for cyclical purchases.
What do you care about what an average American family spends for an average car, if you drive BMW coupes ?
Re: How accurately can we measure INFLATION?
The CPI doesn’t measure how much you or the average American paid for a BMW or Honda, but the change in price for the BMW or Honda.
One thing that humbles me deeply is to see that human genius has its limits while human stupidity does not. - Alexandre Dumas, fils
Re: How accurately can we measure INFLATION?
Actually, "CPI" stands for "Consumer Price Index". It measures monthly the average price of the average consumption for the average family. Inflation is the rate of change of CPI values.
abhikush won't get any useful information about his personal inflation rate from BLS. He knows what he regularly purchases and how much he pays for it; the BLS does not. For less frequent purchases, either they are small and they don't matter, or they are large and he will promptly find info about the current price of a BMW on the BMWusa website. Then, again, if he is not buying a BMW now, what does its current price matter ?