Prices Archive

Historical Stock Price Data from Way Back

What is that which hath been? it is that which is, and what is that which hath been done? it is that which is done, and there is not an entirely new thing under the sun.

–Ecclesiastes 1:9

Click here to skip the commentary.

One thing I’ve heard from some of the top minds in economics: When modeling financial data, it is critical to use data extending as far back as possible. While occasionally there are good reasons to utilize only a subset of a given series in a particular model, modeling the maximum timespan for which data are available is generally a good idea, especially when analyzing risk. After all, if you don’t look back more than several decades, how can you expect to anticipate a systematic crash that occurs once a century?

Now, nobody is arguing that data from the far-flung past is a panacea. Sometimes it can be downright misleading. There are several things to watch out for when analyzing historical series from far in the past:

  1. The quality of data from the distant past varies. Some of it is extremely accurate; some if it is not. In many instances, there is no way to verify its accuracy.
  2. In some cases, historians have provided approximations for missing entries in historical data. Usually this is clearly identified, but there is no guarantee. Approximated series may not be appropriate for some types of analysis, and a historian’s choice of approximation scheme may not always match yours.
  3. Methodologies used in historic times may vary greatly from modern standards and may even vary unexpectedly within the same dataset. Recently recorded data is often higher quality than data from the distant past.
  4. There have been major systematic changes in economic systems. Nations have gone from communist to capitalist, from autarchies to participants in the global economy. Resources have dried up and been discovered. New discoveries have been made, and old inventions have gone out of use. Sometimes, historical data from far in the past simply isn’t relevant in modern times.
  5. There have been major systematic changes in financial systems. Metallic standards have come and gone. Central banks have reigned and been dissolved. Financial systems have increased enormously in terms of speed, transparency, and efficiency.
  6. There have been major changes in market philosophy. Some of these changes have had an impact on market psychology.
  7. There have been major changes in political systems. Wars, treaties, securities regulations–the list goes on.
  8. Of course, past performance is not necessarily an indicator of future performance. In particular, when market participants and other entities have the benefit of hindsight, they may act far differently than they did in the past, and anticipating their decisions is not always easy.

Nonetheless, there are striking similarities between modern markets and those of times long ago. Traders still pace the floor of the New York Stock Exchange. Communication systems have improved, but even so, it’s really not that much faster to place a trade by ECN than it was to place one by telephone 30 years ago–or even by telegraph 150 years ago. Sometimes, the revelations held in historical data are surprisingly relevant even in modern times.

more to come

twitter Historical Stock Price Data from Way Backdigg Historical Stock Price Data from Way Backreddit Historical Stock Price Data from Way Backemail Historical Stock Price Data from Way Back

Chart of the Day 2010/05/24: An Anomaly in IMF SDR/USD Exchange Rate Data

Inspired by the recent Dow in Gold chart that has been making its way around the blogosphere, today I intended to put out a chart of the S&P in SDRs. But after downloading the SDR per USD historical series directly from the IMF using their Exchange Rate Query Tool, I noticed a strange anomaly. It looked almost like two series were super-imposed on the graph. Examination of the raw data revealed extremely large short-term oscillations over a range of dates spanned by 1994 to 1997, some exceeding 15%. For historical purposes, I have pasted a snapshot of my browser window below. You can see the oscillations in the table:

snapshot1 Chart of the Day 2010/05/24: An Anomaly in IMF SDR/USD Exchange Rate Data

I haven’t found a good explanation for this bizarre reporting by the IMF, but they do offer a series of monthly spreadsheet downloads, formatted for legal paper (available from the form at the bottom of the linked page, not the query tool). The umm… “legal” series doesn’t seem to be affected by the anomaly, but my statistical software doesn’t like the formatting. So it will be a little while until I release a chart of the S&P in SDRs, but I’ll try to get it out soon.

Update 2010/05/25: I converted the “legal” series to CSV and prepared a chart of the S&P 500 in SDRs.

twitter Chart of the Day 2010/05/24: An Anomaly in IMF SDR/USD Exchange Rate Data digg Chart of the Day 2010/05/24: An Anomaly in IMF SDR/USD Exchange Rate Data reddit Chart of the Day 2010/05/24: An Anomaly in IMF SDR/USD Exchange Rate Data email Chart of the Day 2010/05/24: An Anomaly in IMF SDR/USD Exchange Rate Data

Chart of the Day 2010/05/21: Median CPI

A question that often gives rise to difficulties: How to gauge inflation?

The well-known and often-used CPI-U measure is not without its detractors. A particular problem with the CPI-U is that it is highly volatile. A short-term change in a heavily-weighted component, such as gasoline, can cause the index to fluctuate wildly.

One solution often employed for cutting through the volatility is to drop a subset of the most volatile components, particularly, food and energy prices. The resulting measure is called core CPI. Another solution is maintained by the Cleveland Fed: an index it calls median CPI. Rather than simply dropping a subset of the most volatile components from the index, they instead use a robust measure of central tendency, which they claim allows them to more accurately gauge inflation.

Care should be taken in any substitution of median CPI for other measures of inflation; while it appears to provide a more robust gauge of trends in inflation than some other measures, as a measure of the average change in the prices paid by the average consumer, it is biased. It instead reflects the change in the average price paid by the average consumer, a subtly different measure.

twitter Chart of the Day 2010/05/21: Median CPIdigg Chart of the Day 2010/05/21: Median CPIreddit Chart of the Day 2010/05/21: Median CPIemail Chart of the Day 2010/05/21: Median CPI

Chart of the Day 2010/05/19: CPI and M1 per Person

M1 has shot up stratospherically in the past year and a half. While in some ways a high M1 is not exactly the most encouraging of indicators (and I haven’t run any models), deflation looks unlikely.

Update 05:00 AKST: The BLS released CPI estimates this morning. Core CPI (less food and energy costs) was unchanged. The full CPI-U actually decreased 0.1% on a seasonally-adjusted basis due to a 1.4% decrease in energy costs.

Update 14:00 AKST: Great video on Carpe Diem of a Cleveland Fed tutorial on the predictive qualities of median CPI.

twitter Chart of the Day 2010/05/19: CPI and M1 per Persondigg Chart of the Day 2010/05/19: CPI and M1 per Personreddit Chart of the Day 2010/05/19: CPI and M1 per Personemail Chart of the Day 2010/05/19: CPI and M1 per Person

The PPI Provides Poor Measures of Aggregate Inflation

The Bureau of Labor Statistics maintains two major inflation indices, the Consumer Price Index (CPI) and the Producer Price Index (PPI). Since it is more widely used, the CPI is often criticized. I can recall several anecdotes stating that during the administration of

Choose one:

View Results

loading The PPI Provides Poor Measures of Aggregate Inflation Loading ...

hamburger replaced steaks in the CPI, reflecting a lower standard of living for Americans. (Note: unlike many polls, the poll above is entirely unscientific and placed here solely for your own amusement; it serves no other useful purpose.) Without descending too far into sarcasm, I will say that although I haven’t seen the exact details of that particular change to the CPI, it does seem reasonable that changes in the price of hamburger would more accurately reflect changes in the cost of living than would changes in the cost of steak. Note that at the time the decision was made (whenever it may have been), the re-weighting would have had 0 impact on the index reading; future changes in the price of hamburger would be reflected in changes to the index. I don’t necessarily agree with all BLS decisions, and they do update the CPI to reflect changes in lifestyle, but as a tool to measure aggregate inflation, the CPI is actually pretty solid.

On the other hand, the BLS really does make some bizarre decisions in maintaining the PPI. For example, they decided that in late 2009, consumer-grade potatoes nearly halved in their production importance:

Relative importance of component series in the Producer Price Index
by stage of processing, December 2009 1/                                        02/16/10
________________________________________________________________________________________
      |         |                                                 | Relative importance |
      |  Com-   |                                                 |_____________________|
 SOP  | modity  |             Index                               | December | December |
 code |  code   |                                                 |  (2008)  |  (2009)  |
______|_________|_________________________________________________|__________|__________|
3111             Finished consumer foods, crude                        1.751     1.993
        011101   Citrus fruits                                         0.080     0.088
        011102   Other fruits and berries                              0.398     0.486
        011103   Melons                                                0.047     0.037
        011301   Dry vegetables                                        0.035     0.033
        011302   Fresh vegetables, except potatoes                     0.579     0.771
        011303   Sweet potatoes                                        0.005     0.005
        011304   Irish potatoes for consumer use                       0.096     0.053 
        011901   Tree nuts                                             0.095     0.084
        012101   Wheat                                                 0.010     0.009 

It’s hard to say exactly what the logic was behind this particular BLS PPI re-weighting decision. Maybe they thought that Americans were switching to a low-carb lifestyle… Perhaps they felt that changes in the price of consumer-grade potatoes had less impact on manufacturing costs than previously anticipated. That seems reasonable. But then again… why would potatoes have been weighted so much higher just a year previously? Furthermore, should tree nuts really be weighted so high relative to the other commodities? I don’t think there are satisfactory answers to these questions, but if you happen to come up with one, feel free to leave a comment.

For aggregate measures of inflation, the CPI is far superior to the PPI. I don’t generally suggest using the PPI aggregates for any purpose, although when the BLS updates the individual commodity series in a timely manner, it’s not hard to create custom price indices.

twitter The PPI Provides Poor Measures of Aggregate Inflationdigg The PPI Provides Poor Measures of Aggregate Inflationreddit The PPI Provides Poor Measures of Aggregate Inflationemail The PPI Provides Poor Measures of Aggregate Inflation
Partly powered by CleverPlugins.com