gone parabolic (UNCLASSIFIED)

Mullins, Bill AMRDEC Bill.Mullins at US.ARMY.MIL
Thu Dec 2 15:49:27 UTC 2010

Classification: UNCLASSIFIED
Caveats: NONE

> ---------------------- Information from the mail header
> -
> Sender:       American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
> Poster:       Victor Steinbok <aardvark66 at GMAIL.COM>
> Subject:      gone parabolic
> -
> An odd line in a WSJ blog post on the Netflix stock success:
> http://goo.gl/lDRff
> > The chart on Netflix has truly /gone parabolic/ since late January
> Take a look at NFLX stock charts and see for yourself if there is
> anything "parabolic" about them.

The writer, Matt Phillips, probably vaguely remembered the phrase "gone
ballistic" (which would be more appropriate, though still not accurate)
and wrote "gone parabolic" by mistake.

> http://goo.gl/yRpTz
> Although the stock price has been rising fairly steadily over the past
> 11 months (starting from a 1-year low on Jan. 2), the rise has been
> fairly close to linear (with some daily and weekly fluctuations, of

The rise is only "fairly close to linear" if you are looking at in on a
chart the vertical axis of which is logarithmic:


If you look at the history on a chart with a linear vertical axis:


the rise is not linear, but exponential.

> course, e.g., a small drop today). But looking at 3-yr and 5-yr charts
> shows that the price had been fairly flat for a long time through
> October of 2008, then crept up slowly to the end of 2009 (from high
> 10s-low 20s to about $50), and rose much more rapidly in 2010 ($50 to
> $209, having hit $100 in May and August, August being the last "dip").
> There is little doubt that one could fit a parabola to the data, but
> that does not necessarily make the chart "parabolic" (of course, one
> could "fit" a parabola to /any/ chart, with different degrees of
> accuracy). Besides, the claim is not that the chart is parabolic over
> the last 3-5 years, but over the last 11 months, when the growth can
> best be described as linear!
> The question I have is whether this may represent simply an attempt to
> communicate a pattern of sharper increases over shorter periods of
> (which, I suspect, most investors would not understand--and is not
> for the specifically mentioned period) or if the term "parabolic" has
> simply gone hyperbolic, like the much belabored "exponential" (with
> difference being a question of degree--and I don't mean that to be the
> degree of a polynomial). What throws me off is the use of "truly" in
> quoted sentence, but, of course, this may not truly mean "truly" (see,
> for example, all the past threads on "literally" in ADS-L archives). I
> am generally fascinated by odd usage of fairly well-defined
> terms, so this one grabbed me right away.

I think you are giving the writer credit for more precision and
sophistication in his language than he deserves.  The simplest
explanation is that Phillips doesn't know how to use mathematical terms
properly (which is not at all unusual for a journalist).

Classification: UNCLASSIFIED
Caveats: NONE

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