This is a post on how they do it. Just an example, not really up to date data, it is for learning afterall. … For up to data, that you either need to do it yourself, or pay people to do it for you.
The stock market is very sensitive to a calculus concept called “the second derivative.” It’s not that hard to grasp, and I’m certain that if you keep reading you will have no trouble at all understanding it.
How fast are we going? In a car, we measure that speed in miles-per-hour (MPH) here in the USA. Think of your speed as the “first derivative.” Now think about how it feels to be going 70 mph in three different scenarios:
- Cruising at 70 as you drive across Kansas.
- Accelerating from 0 to 70 as you enter the freeway after a rest stop.
- Slamming on the breaks when you see an idiotic deer frozen in your headlights while going 100.
In scenario 3, at some point your speed will drop to 70 as you break. But it feels completely different from the other two 70′s, right? That’s the second derivative in action. In each case, you are going the exact same speed. One is fun as you zoom up. One is dull as you cruise. And one is harrowing as you break and pray that you won’t die.
The same is true for our economy. The actual speed is not as important as how fast the speed is changing and in which direction. After a recession, the stock market rockets up. As the economy cruises along at a steady speed, the market can continue to creep upward. When a recession sets in and the economy decelerates rapidly, the market falls.
Look at it this way, economy acceleration(that’s the second derivative), both plus and minus, shows the direction of the economy, is the economy expanding, minus is contracting.
So, how do we measure the speed of the economy? You can measure it in various ways. The “official” way is to use Gross Domestic Product (GDP), but GDP is unsatisfying because it is only published once per quarter and with a long delay.
Savvy investors like to use the amount of money that the federal treasury is raking off of paychecks each day because that number is published every business day. It is also a good speed measure since the number of people working and getting paid is a very good indicator of how well the economy is doing.
So, instead of miles-per-hour that we use in our car, let’s use tax-dollars-per-year to measure the speed of our economy:
Now let’s calculate the second derivative. Don’t panic! It’s not that hard. We don’t even need to use calculus. In fact, we are just going to do simple arithmetic. Let’s look at the chart:
So you see, the second derivative is the time rate of change of the economy.
The chart starts at the left just under 10%. That’s how much we sped-up in 2000 compared to 1999. Here is the calculation:
1999 taxes = 1,261,750,000,000
2000 taxes = 1,381,625,000,000
1,381,625,000,000 – 1,261,750,000,000 = 119,875,000,000
So, the treasury raked in $119,875,000,000 more dollars in 2000 than it did in 1999. To find the percentage, we divide that gain by the 1999 total:
119,875,000,000 / 1,261,750,000,000 = 9.5%
Easy, right? Now when we do that calculation for each year, and then plot it on the chart above, we get a second-derivative chart. A chart that shows us how much the economy accelerated or decelerated from year-to-year. That’s all there is to it.
So, on the first chart, it didn’t look like anything important was happening in 2007. But on the second chart, it was clear that tax collections were in decline. That was a good early warning for the recession which was about to begin.
Note: the charts above are based on the federal government’s fiscal year, which begins in October, rather than January.
See the upturn?
More here:
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