There are hopeful signs that

[bodhisattwabiswas]

* The air quality of Las Vegas was higher in 2007 than it was in 1997.
--> This version is correct, since "it" stands for "the air quality of Las Vegas".


You can also just write "The air quality of LV was higher in 2007 than in 1997."

thanks for the explanation... and we can't use 'that' instead of 'it', as "that"/"those" can't be used as a standalone pronoun while comparing; am I right?

[tim]

No; "that" just doesn't work with a verb here the way "is" does. Let us know if you have followup questions; there's a lot here, but I want to help with specific questions you might have.

[divineacclivity]

Ron,

is there a difference between the following two sentences?
Are both correct?
:
"Rate of increase of X is twice as fast as that of Y"
"Rate of increase of X is two times faster than that of Y"
-----------------------------------
In the 1980’s the rate of increase of the minority population of the United States was nearly twice as fast as the 1970’s.

(A) twice as fast as
(B) twice as fast as it was in
(C) twice what it was in
(D) two times faster than that of
(E) two times greater than

[RonPurewal]

Both incorrect.

You can't say that a rate is "fast(er)".
The increase itself was faster; the rate was higher.

Read more here:
post44894.html#p44894

[RonPurewal]

"Twice as fast" and "two times faster" are mathematically distinct.
Twice as fast = 2 x rate
Two times faster = 3 x rate

The difference is clearer if "two times" is replaced by, say, "50 percent":
50 percent as fast = 0.5 x speed
50 percent faster = 1.5 x speed
The first example is the same as this one, but with "2 times" = 200% instead of 50%.

--

On the other hand, this is not the quant section, so mathematical differences are irrelevant.

[divineacclivity]

Both incorrect.

You can't say that a rate is "fast(er)".
The increase itself was faster; the rate was higher.

Read more here:
post44894.html#p44894

From you other post:
a rate can't be fast (just as a height can't be tall, and a price can't be expensive

Superb example, Ron. You make learning so much easier. Thank you.

[divineacclivity]

"Twice as fast" and "two times faster" are mathematically distinct.
Twice as fast = 2 x rate
Two times faster = 3 x rate

The difference is clearer if "two times" is replaced by, say, "50 percent":
50 percent as fast = 0.5 x speed
50 percent faster = 1.5 x speed
The first example is the same as this one, but with "2 times" = 200% instead of 50%.

--

On the other hand, this is not the quant section, so mathematical differences are irrelevant.

Thank you, thank you, thank you, Ron. That perfectly answers my question :)

[Tadashi]

Hi Ron,
an easy question for you.
Can we say "more than ten times as much energy is generated through wind power now as the case was in 1990"?

I know that we can say "I love ice-cream more than do you."

Thanks,
Tadashi.

[RonPurewal]

Hi Ron,
an easy question for you.
Can we say "more than ten times as much energy is generated through wind power now as the case was in 1990"?

I know that we can say "I love ice-cream more than do you."

Thanks,
Tadashi.

No.

This is covered in the discussion containing the following post:
post96035.html#p96035

[Tadashi]

Great!
Thanks
Tadashi

[RonPurewal]

You're welcome.

[benjamindian]

* the air quality of las vegas was higher in 2007 than that in 1997
--> INCORRECT
this isn't parallel; the left-hand structure is interrupted by a verb, while the right-hand structure contains no such verb.

Hi Ron,
For the question below, following your example above and "Beauty Contest" mentality, I eliminated the correct answer B simply because I didn't find a ".... in" parallel structure before "than" and chose the typical ambiguous answer E:(

In addition to having more protein than B does, the protein in A is higher quality than that in B, with more of the blah blah.

B)A has protein of higher quality than that in
E)A has a protein higher in quality than

So I think in your incorrect example above, it might be correct if there is no better choice present. i.e. I think if the answer choice has "Nouns that/in/of..." and "those that/in/of" as parallel structure, that will be the best answer.

e.g.
Many teenagers ......., but results of a recent study indicate that the patterns of stress that girls experience are more likely to result in depression than are those that boys experience.

But when there is NO exact structure before the comparison indicator, "that/those" can still be used to make a new copy in the second part.

e.g.
Recent breakthroughs .... have made it possible for HD digital video cameras to capture material with a degree of fidelity nearly comparable to that (i.e. the degree of fidelity - Make a New Copy) of 35-millimeter film and to ....

Please correct my understanding. Thanks!

[RonPurewal]

So I think in your incorrect example above, it might be correct if there is no better choice present

this ^^ is what i mean when i say "parallelism is a beauty contest".

of course, if there are any choices with perfect parallelism, then the beauty contest idea is unnecessary-- you'll take those and reject the others.
in all other cases, though, just make relative judgments.

beyond that, i don't see any other issues raised in that post.

[benjamindian]

Hey Ron,

Thanks! Yeah, since it's a contest, I have to pick the best of the five even if that winner is a little uglier than I expected.

[RonPurewal]

...exactly.