My maths is so bad that no, I can’t do this.
OK, what was the growth rate 1929 to 1938? What was the growth rate 1945 to 1980? The growth rate 1980 to today?
And, finally, what was the growth rate 1929 to today?
Just the average over those selected years. So, total growth rate over that period divided by number of years.
Anyone who can actually use a calculator care to do that for me?
1929 = 1191.124
1938 = 1214.869
1214.869/1191.124 = 1.0199
over 9 years, so 9th root(1.0199) = 1.00219561
So 0.219561% per year
1945 = 2500.057
1980 = 7257.316
7257.316/2500.057 = 2.90286021
over 35 years, so 35th root(2.90286021) = 1.03091677
So 3.091677% per year
1980 = 7257.316
2025 = 23864.462
23864.462/7257.316 = 3.28833166
over 45 years, so 45th root(3.28833166) = 1.02680588
So, 2.680588% per year
1929 = 1191.124
2025 = 23864.462
23864.462/1191.124 = 20.0352457
over 96 years so 96th root(20.0352457) = 1.03171646
So, 3.171646% per year
Cavat emptor. You can have the extra decimal points for free.
To be explicit with the calculator operations:
1929 = 1191.124
2025 = 23864.462
23864.462/1191.124 = 20.0352457
over 96 years so 96th root(20.0352457) = 1.03171646
Subtract 1, multiply by 100
So, 3.171646% per year
right brain engaged – so if i get that correct you have calculated the actual growth by looking at the GDP in the start and end year over the period and worked back to get an annual average growth rate.
If I work out each years growth and average the growth I get:
1929-1938 0.59538076070198
1945-1980 3.04665507982775
1980 to date 2.63324267623146
1929 to date 3.27961377807273
chart attached – not sure if it will work
Thank you that is much more useful than numbers.
can probably get it working with proper labels and everything if need be!
I’m even lazier than Tim: https://www.omnicalculator.com/finance/cagr
1929-1938 1076.4453
1945-1980 4286.38619444444
1980 to date 14635.5036304348
1929 to date 8683.85310309278
just mean averages over the period – simple librecalc
spreadsheet if you want to tinker
ok just ignore me – cognitive functions impaired today!
And the growth rate 1938 to 1945 was 10.859867% per year !!!!
Shows the idiocy of including government spending (in this case on World War II) in the GDP figures.
I carefully stepped aside that….
Since 1865, America has been lucky in its wars. They’ve all been away games. Although Walz and the Dems are trying their hardest to correct that.
Glad to see that jgh who beat me to it has correctly prodiced CAGR instead of the almost meaningless straight-line figures beloved of the innumerate and propagandists.
Is it St. Pendant’s Day today?
It’s always St Pedant’s Day on here. This place is nearly as bad as Samizdata.
Pendantically, it’s always St Pendant’s Day here
I was actually surprised that 1945-1980 was higher than 1980-2025, but I suppose the post-war rebuilding boosts the first part, but makes me wonder what suppressed the second part.
The decade of 1970-1980 saw the post Vietnam defense drawdown and numerous oil crises. Not helped by political instability surrounding Nixon, and the always feckless Carter.
What suppressed economic growth in 1980-2025?
What about the fallout from the collapse of the Clinton sub-prime housing boom in 2008? The government shutting down large parts of the economy in 2020/21?
“total growth rate over that period divided by number of years.” No ….!
JGH shows you how to get the “geometric mean” which is what you want.
Surely you were taught to do this at school using logarithms? Shoulda gone to Ampleforth.
I’ve just realised what’s missing today. Any reference to Saturday’s rugby.
Surprised, are you?
I do have the highlights of the England v Ireland game
…what was the [US] growth rate 1929 to 1938? What was the growth rate 1945 to 1980? The growth rate 1980 to today?
Er…use AI?
It’s as easy as just pasting the text then waiting. for a couple of minutes:
https://grok.com/share/c2hhcmQtMi1jb3B5_fc85c3ad-a810-4d76-9195-c0302aa8c663
If you click on the little light bulb by “though for 2m 34s” at the top it will show you the methodology to give the answer…….. which being AI might be wrong though it seems close to other answers and its always interesting to discover what it chooses as sources.
Or 2 seconds using a calculator, if you understand compound interest (which I was taught in primary school).
2 seconds to locate a suitable source, select the right years, then type the numbers and do the calculations for each of the half dozen results needed Really?
Like you I did compound interest at junior school (just compounding the initial sum rather than working out the rate as that was hard in pre-calculator days). Now in this instance it’s the simple part of the task.
The AI solution took the exact text Tim typed and did the whole process. My copying the text from Tims blog and pasting in into the AI was a 2 second task. It took it a while to process as I was of course using a free version.
You know there’s a calculator included with your OS, I suppose?
Whoa whether we use base growth or CAGR is a tad academic. Govermnets can distort this. Shouldn’t we be looking at Private Sector GDP or Disposable Income per Capita?
That depends on what you want to measure but your two suggestions have measurement problems – governments distort “Disposable Income per Capita” every time they change taxes and “Real” “Disposable Income per Capita” every time they freeze tax threshholds. When Lady Thatcher privatised state-owned monopolies she significantly increased Private Sector GDP while reducing “Real GDP” by forcing them to cut prices in “Real terms”.
GDP wasn’t invented until 1934.
It’s fascinating to see 8 places of decimals being used for something you couldn’t know to the accuracy of a couple of percent.
Hindsight is a wonderful thing, and calculations on a multi year basis help precision. But yes even so, one or at most two places would be more appropriate.