January 5, 2016

Some things don’t need exaggerating

Stuff:

The Dow Jones industrial average was set for its worst start to a year since 1932 as stock markets tanked after weak Chinese economic data reignited fears of a global slowdown.

Herald

The U.S. blue-chip index tumbled toward its worst start to a year since 1932, while banks and technology shares led the Standard & Poor’s 500 Index lower.

That’s presumably true, and bad news, but “start to a year” is doing a lot of work. Here’s the past year’s Dow:

dow

Unless there’s something especially predictive about the first trading day of the year, this is no worse than some quite recent days. And, the Herald says further down in the story

S&P Dow Jones Indices data indicate the first day of trading has no predictive power for the rest of the year. The index ends the year in the same direction it takes on the opening day 50.6 percent of the time, the data show. The first month of the year has proved more telling — the gauge’s return in January determines its direction for the year 72.4 percent of the time.

 

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    Nick Iversen

    Auckland got off to a pretty bad start to the year in terms of rainfall. The first day of January had 34mm of rain compared to the mean of 2mm. That’s 17 times the mean and if that continues every day we will get about 20 metres of rain this year. That’s more than the West Coast of the South Island.

    9 years ago