When you go to the doctor for a check-up, several tests are performed. The specific tests which are performed--eg, pulse rate, blood pressure, body temperature, etc.--are performed because those tests are good at providing your doctor with meaningful information about your health.
Results of those particular tests, provide good estimation of your health.
That's because they have both accuracy and reliability. An accurate test truly tells you something about what you are seeking to know--it tells you that recorded differences truly are meaningful in a way in which you should care.
A reliable test is so sensitive to alterations that all, or almost all, of the meaningful difference gets captured and recorded by the test. Here is an illustration of accuracy and reliability with regard to hitting the bullseye in archery:
Researchers sometimes call accuracy "specificity" because the test specifically singles out the target condition, and they sometimes called reliability "sensitivity" indicating that measurement tools are sensitive enough to catch all meaningful change.
You need a good amount of both of them in order for a test to be a good test.
Those two things--the accuracy and reliability--explain how to go about testing a person's physical health or well-being, but what about our material well-being? Which test provides good estimation of an entire nation's economic health?
Perhaps the single best test, providing the most unbiased estimate of a nation's economic health, is the ratio of total (all-sector) debt to the median money income (income which could conceivably be directly applied to debt payments).
The ideal income to use here would actually be the market income--the income received for services provided, either through providing capital or labor--but money income will have to suffice for now, due to my current lack of data on market incomes.
I begin below with the most common measure: mean (average) income.
Total debt held, divided by total money income, is a measure of debt leverage. The debt leverage let's you know how much debt is required in order to maintain a lifestyle.
In healthy economies, even high living standards are affordable, and there is no requirement for any escalation in the ratio of debt-to-income (nominal, or raw, debt may rise slightly faster due to being the larger value in the ratio, even though the ratio does not change).
The affordability of a living standard tells you how well off you are.
The mean income in a nation is overall income divided by overall people (or households, or families, or workers, etc). It can be increased by increasing national output. When all of the increase in the mean income comes solely from an increase in national output, debt does not have to rise.
Another way to increase mean income, but one which also causes debt to rise, is through government transfers (subsidies, welfare, etc.). Government transfers are income, but they are not income for services provided, either through providing capital or labor.
Such transfers are not income which is fully paid for (fully funded) by productive activity tied to consumption through market mechanisms.
When mean income gets raised primarily through government transfers--rather than through extra market productivity--debt rises along with it, so that economic health has not improved (even though mean income did).
Another non-market way to artificially raise mean income is through inflation, but inflation increases debt, too. This is primarily because it induces recessions:
By pitting the nation's producers--ie, the cheap credit inflates long-run production bubbles--against the nation's consumers, whose consequently-low real savings rates induce over-consumption, depleting the very savings which would have been required to buy the long-run goods that the producers have started "over-producing" (because of the cheap credit).
With government intervention, both fiscal (tax & spend) policy and monetary (inflation/cheap credit) policy can artificially raise mean incomes, but not without increasing debt. This makes debt-adjusted real mean income (DARMnI) into an accurate measure of economic health, but is it the best measure?
While inflation and non-market transfers can easily raise nominal mean income, they cannot--just as easily--raise median income. This is because interventions misallocate the resources of society, disconnecting market participants who were relying on economic signals from each other.
Instead of spontaneous order, new pockets of wealth concentration and also of poverty begin to arise. Cronies practicing "regulatory capture" will be able to charge a "rent" to society, a concentration of wealth which would not have occurred under free (unregulated) market mechanics.
Also, cash transfers disincentivize economic activity, so the spread of incomes grows larger from both ends at the same time. Interventions then cause an increase in income inequality--via misallocation and perverse incentives--even while the mean income rises.
The mean income rises but, because of misallocations and perverse incentives, the median income lags behind. And, because the overall size of the economic pie did not keep up (because the extra income didn't come from extra market productivity), debt rises by an amount we will call amount "A".
While debt-adjusted real mean income (DARMnI) is accurate, it is not fully reliable and precise--because the extra debt incurred from interventions can be somewhat hard to detect.
But what those interventions cannot do as well--not without causing EVEN MORE DEBT than raising the mean income would have--is to increase the real median income.
If a government tries to raise median income artificially (through non-market means), then debt rises by an amount (amount "B") which is even farther and easier to detect than amount "A". [see endnote]
While debt-adjusted real mean income (DARMnI) and debt-adjusted real median income (DARMdI) are both accurate tests--ie, both tell you what it is you were seeking to know (economic health)--DARMdI is more reliable and precise, because debt caused by the non-market interventions required to artificially raise median income is even easier to detect than debt caused when raising mean income.
Debt-adjusted real median income is not just an accurate measure of economic health, but it is also very sensitive to changes (reliable).
Total debt , divided by total US families , is currently over 10 multiples of the median family income .
The US economy was much healthier in the 1950s, 1960s, and 1970s--when total debt divided by total families was less than 4 multiples of the median family income (and even less than 3 multiples of median income in a couple of the years!):
High living standards were more affordable a half-century ago than they are today. Before 1979, median income rose fast and per-family total debt did not rise by any meaningful amount--indicating lots of economic health.
After 1979, per-family total debt rose fast and median income did not rise by any meaningful amount--indicating a cumulative decline in economic health.
To restore economic health, we must restore economic freedom--we must have the federal government making less regulations than it has been making, and making less cash transfers and other economic interventions than it has been doing.
A "good" or at least a "healthier" amount of regulation and spending would mirror that of 1950, when there were less than 10,000 total pages of federal regulations , and the federal government spent less than 16% of GDP [5 & 6].
This level of intervention is much less than the current level, where there are now over 180,000 pages of federal regulations, and we have a level of federal spending that is now over 21% of GDP.
Amendments to the US Constitution could be proposed, debated, and ratified without permission from Congress, by using the means provided to us--in Article V--by those who framed the US Constitution. Three possible amendments might look something like this:
28th Amendment: The Code of Federal regulations shall remain below a total length of 10,000 pages.
29th Amendment: Federal spending shall remain below 16% of the annual average GDP of the previous 3 years.
30th Amendment: No federal official may remain in high office for more than 12 years total (the cumulative sum of all time spent in all high offices).
Endnote: The only way to raise real median income without also adding detectable amounts of debt, is through maintaining economic freedom (capitalism)--because the growing size of the economic pie fully funds the increase in median pay, but raising real median income by other means does not.
Capitalism is the only thing that creates and sustains a vibrant middle-class. Any drift away from capitalism destroys the vibrancy of the middle-class and freezes upward mobility via a protectionist (feudalist), crony-bureaucracy of rent-seeking elites:
The middle class is the heart, the lifeblood, the energy source of a free, industrial economy, i.e., of capitalism; it did not and cannot exist under any other system; it is the product of upward mobility, incompatible with frozen social castes. Do not ask, therefore, for whom the bell of inflation is tolling; it tolls for you. It is not at the destruction of a handful of the rich that inflation is aimed (the rich are mostly in the vanguard of the destroyers), but at the middle class.
--“The Inverted Moral Priorities,” The Ayn Rand Letter, III, 21, 2 [http://aynrandlexicon.com/lexicon/middle_class.html]
 Board of Governors of the Federal Reserve System (US), All Sectors; Debt Securities and Loans; Liability, Level [TCMDO], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/TCMDO
 U.S. Census Bureau, Historical Family Tables (Table FM-1), retrieved from: census.gov/data/tables/time-series/demo/families/families.html
 U.S. Census Bureau, Median Family Income in the United States [MEFAINUSA646N], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/MEFAINUSA646N
 Regulatory Studies Center website at the Columbian College of Arts & Sciences (George Washington University)--scroll down to the Code of Federal Regulations entry. https://regulatorystudies.columbian.gwu.edu/reg-stats
 U.S. Bureau of Economic Analysis, Federal Government Current Expenditures [AFEXPND], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/AFEXPND
 U.S. Bureau of Economic Analysis, Gross Domestic Product [GDPA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/GDPA