gone parabolic (UNCLASSIFIED)

[Joel S. Berson]

Isn't there something wrong in the first place of thinking of
increasing curvature with a parabola?  As the arms of a parabola move
further away from the center, doesn't the curvature continually
diminish and approach a straight line?

The analogy of ever increasing values to a parabola seems to me
instead the progression of the arms to infinity, as contrasted with
the other conic section, the ellipse, which closes upon itself.

Joel

At 12/2/2010 10:49 AM, Mullins, Bill AMRDEC wrote:
>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
> >
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>------
> > -
> >
> > 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
>2010.
> >
> > 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:
>
>http://finance.yahoo.com/q/bc?s=NFLX&t=2y&l=on&z=l&q=l&c=
>
>If you look at the history on a chart with a linear vertical axis:
>
>http://finance.yahoo.com/q/bc?s=NFLX&t=2y&l=off&z=l&q=l&c=
>
>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
>time
> > (which, I suspect, most investors would not understand--and is not
>true
> > for the specifically mentioned period) or if the term "parabolic" has
> > simply gone hyperbolic, like the much belabored "exponential" (with
>the
> > 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
>the
> > 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
>mathematical
> > 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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