Five times less

[Victor]

I have several possible interpretations of the "300% decline". First,
one should always consider typos, of course, but that's not an issue
when the number is spoken. So here are the alternatives--feel free to
accept or reject for plausibility.

1) The person performing the calculations might have reversed the
referent quantity, taking the final value as 100% instead of the
initial. So the actual decline would have been 75%.
2) The reporter misinterpreted 300% inflation as a 300% decline in
value--this is somewhat understandable because inflation represents
decline in value. However, this still makes for a ridiculous conclusion.
In this instance, even if we are talking about 300% inflation, it is
impossible to tell if it is exact or annualized (in which case, the
actual decline would be more like 25%). Inflation is a black box for
most reporters and the mere association with decline in buying power may
be enough to cause the error.
3) There may have been a previous record of decline in value and the
reported rate is simply either 3 times or 4 times that rate. So it's not
that the "value declined by 300%", but the rate of decline increased by
300% (or simply *is* 300% of the earlier rate--hence the 3x vs 4x
discrepancy). Obviously this cannot be resolved without actual data. The
confusion of increase vs. relative increase (i.e., the change in the
increase) is a common one is a the usual fodder of political discourse.
It is quite common for an average opponent of a budgetary item to
complain about the double or triple-digit percent "increase" in spending
when what he means is the actual increase in the change in spending.
That is, if a program received $100 one year, then $101 the next year,
and is projected to receive $103 in the next budget, it would not be
uncommon to hear a complaint of doubling the expenditure on the program.
It is ridiculous at face value, but that's the level of discourse that
we have. Often, this is coated in doublespeak, so that the actual
statement may be true, but it is designed to be misinterpreted by the media.

In this particular instance, the inflation explanation appears to be
most likely. I am not sure what the situation is with the "murder rate"
decline. I am inclined to believe that this means that after an x%
increase in the murder numbers, the next change is the x% decline, thus
making a 100% reversal in the "acceleration" rate, of sorts.

My interpretations of student answers that resemble these situations are
usually based on full context of the problem. Here, I am operating
somewhat blind, lacking most of the context, including the "actual"
data. Hence the speculations. When it comes to statistics--even the kind
of recurring financial statistics that they see regularly--most
reporters are clueless. Add to this the pressure to avoid duplicating
sources word-for-word (which is what passes for plagiarism these days),
and this is what you find.

    VS-)

Arnold Zwicky wrote:
> On May 22, 2009, at 8:21 AM, Bill Palmer wrote:
>
>
>> Very helpful & interesting reading, Arnold, and thanx. I have a
>> corollary.
>>
>> On the local AM radio station, I was informed that the murder rate
>> in North
>> Carolina had "declined by over 100%".  One can muddle thru a "five
>> times
>> less" construction and figure out what was meant, but how is it
>> possible to
>> reduce something by more than 100%?
>>
>
> squirreled away for eventual attention is this message i got last
> august from a Language Log reader:
>
>    I just wanted to share a favorite quote of mine which I heard on
> NPR during a discussion of the Russian economy, back when its currency
> was in a free-fall. The reporter announced in all seriousness that the
> currency had lost value "by 300% in the past month". I pictured it
> losing 100% of its value. Okay, now it is worthless. I started to
> imagine negative currency value. What would it mean to have a currency
> at -200% value? Or do they pay you?
>
> .....
>
> i think i've seen others of this sort.  i haven't done anything about
> them because i don't really know what the speakers/writers were trying
> the convey; maybe asking them would shed some light (but maybe not).
>
> sometimes people who send me these things just dismiss the responsible
> people as "innumerate".  but that treats such things solely as
> mathematical expressions, whereas they are clearly supposed to be
> ordinary english with some things from the mathematical lexicon in
> them.  they don't follow the rules of "mathematical english", but we
> should give the responsible people some credit for having a system,
> even if it's not the system mathematicians use.  the question is what
> this system is.
>
> it's much like non-standard variants that don't involve mathematical
> material.  many people are inclined to just dismiss them as
> "mistakes", but linguists always work from the hypothesis that they
> have some system, just not the standard system, and the research
> question is to find out what this system is.
>
> arnold

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