• Free Veritas GMAT Class
Experience Lesson 1 Live Free

Available with Beat the GMAT members only code

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Free Trial & Practice Exam
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

• 5 Day FREE Trial
Study Smarter, Not Harder

Available with Beat the GMAT members only code

• Award-winning private GMAT tutoring
Register now and save up to \$200

Available with Beat the GMAT members only code

• 5-Day Free Trial
5-day free, full-access trial TTP Quant

Available with Beat the GMAT members only code

• Free Practice Test & Review
How would you score if you took the GMAT

Available with Beat the GMAT members only code

• Reach higher with Artificial Intelligence. Guaranteed
Now free for 30 days

Available with Beat the GMAT members only code

## negative correlation - how?

This topic has 2 expert replies and 6 member replies
kunalkulkarni Senior | Next Rank: 100 Posts
Joined
07 May 2012
Posted:
34 messages
2

#### negative correlation - how?

Sat Feb 09, 2013 5:23 pm
there are 2 sets of data:
X = {0,0,0,4,4,4,6,6,8}
Y = {50,38,56,34,32,42,28,34,29}
There is a negative correlation between X and Y.

Can anyone please explain me. how is the above statement true?
My understanding is as follows:
positive correlation - directly proportional
negative correlation - inversely proportional

Kunal

mkdureja Senior | Next Rank: 100 Posts
Joined
04 Jan 2013
Posted:
38 messages
11
Thu Feb 14, 2013 12:55 am
As per my understanding, correlation is a statistical term with a proper formula. Its value varies from -1 to +1 for any set of data, with value of +1 representing perfect linear positive correlation (data set will draw a straight line in cartesian plane), similarly -1 represents a straight line with negative slope.
Basically, for any given set of data, even random, correlation will be either positive or negative, close to zero for highly uncorrelated/random data.
In the above question, it is clear that when X increases, Y decreases, other than for some exceptions, which can be ignored.

This is my understanding, open for other explanations.

### GMAT/MBA Expert

Tommy Wallach GMAT Instructor
Joined
21 Jan 2010
Posted:
451 messages
Followed by:
114 members
188
Target GMAT Score:
800
GMAT Score:
770
Thu Feb 14, 2013 9:31 am
Hey Mk,

While all that you said may be true, advanced statistics aren't really tested on the GMAT. So you don't need to know much other than a pure positive or a pure negative correlation (i.e. When X goes up, Y goes up; or when X goes down, Y goes up).

-t

_________________
Tommy Wallach, Company Expert
ManhattanGMAT

If you found this posting mega-helpful, feel free to thank and/or follow me!

Free Manhattan Prep online events - The first class of every online Manhattan Prep course is free. Classes start every week.
hemant_rajput Master | Next Rank: 500 Posts
Joined
22 Apr 2012
Posted:
447 messages
Followed by:
13 members
46
Test Date:
25/08/2014
GMAT Score:
700
Sun Feb 10, 2013 5:56 am
kunalkulkarni wrote:
there are 2 sets of data:
X = {0,0,0,4,4,4,6,6,8}
Y = {50,38,56,34,32,42,28,34,29}
There is a negative correlation between X and Y.

Can anyone please explain me. how is the above statement true?
My understanding is as follows:
positive correlation - directly proportional
negative correlation - inversely proportional

Kunal
Hi kunal,

Your understanding of negative correlation is perfect. Here, we have two sets, X and Y. These two sets are in negative correlation because, with every increase in the value of element in X, value of element in Y is decreasing.

0 - 50************************
***********0 - 38 ************
************************0 - 56
4 - 34************************
***********4 - 32*************
************************4 - 42
6 - 28************************
***********6 - 34*************
************************8 - 29

I hope this pictorial representation will make it easy for you to comprehend.

_________________
I'm no expert, just trying to work on my skills. If I've made any mistakes please bear with me.

Last edited by hemant_rajput on Sun Feb 10, 2013 8:33 pm; edited 1 time in total

kunalkulkarni Senior | Next Rank: 100 Posts
Joined
07 May 2012
Posted:
34 messages
2
Sun Feb 10, 2013 12:15 pm
Hey Hemant,
So the main catch is to find the transitioning numbers as X changes from 0 to 6. Just to ensure I understood it correctly, if below was the series for X and Y
0 - 50
0 - 38

4 - 42
4 - 36

6 - 32
6 - 40

then it would be impossible to find negative or positive correlation. right?

Thanks,
Kunal

hemant_rajput Master | Next Rank: 500 Posts
Joined
22 Apr 2012
Posted:
447 messages
Followed by:
13 members
46
Test Date:
25/08/2014
GMAT Score:
700
Sun Feb 10, 2013 8:34 pm
Hi Kunal,

I did some modification in pictorial representation in my previous post. I guess BTG post skips white space in forum. Hope this make it clear.

_________________
I'm no expert, just trying to work on my skills. If I've made any mistakes please bear with me.

### GMAT/MBA Expert

Tommy Wallach GMAT Instructor
Joined
21 Jan 2010
Posted:
451 messages
Followed by:
114 members
188
Target GMAT Score:
800
GMAT Score:
770
Sun Feb 10, 2013 10:45 pm
Hey Kunal,

You are correct. In that set, there wouldn't be a correlation you could call either positive or negative.

-t

P.S. Indeed, BtG does not like white spaces in posts. It's a bit like trying to leave silence on your iPhone voice mail. Ever tried it? No dice.

_________________
Tommy Wallach, Company Expert
ManhattanGMAT

If you found this posting mega-helpful, feel free to thank and/or follow me!

Free Manhattan Prep online events - The first class of every online Manhattan Prep course is free. Classes start every week.
kunalkulkarni Senior | Next Rank: 100 Posts
Joined
07 May 2012
Posted:
34 messages
2
Sun Feb 10, 2013 11:38 pm
Thank you Hemant and Tommy. Appreciate your help.

Cheers,
Kunal

tabsang Senior | Next Rank: 100 Posts
Joined
13 Jun 2011
Posted:
64 messages
5
Target GMAT Score:
750+
Tue Sep 17, 2013 9:14 pm
Hey Kunal,

Could you please elaborate on this.
I'm not quite sure that I got this

Cheers,
Taz

kunalkulkarni wrote:
Hey Hemant,
So the main catch is to find the transitioning numbers as X changes from 0 to 6. Just to ensure I understood it correctly, if below was the series for X and Y
0 - 50
0 - 38

4 - 42
4 - 36

6 - 32
6 - 40

then it would be impossible to find negative or positive correlation. right?

Thanks,
Kunal

_________________
If this post helped you in your GMAT prep, please take a moment and hit the "thanks" button. It'll make my day
---------------------------------
Genius gives birth to great work; labor and labor alone realizes it.

### Best Conversation Starters

1 lheiannie07 80 topics
2 LUANDATO 62 topics
3 ardz24 52 topics
4 AAPL 47 topics
5 Roland2rule 43 topics
See More Top Beat The GMAT Members...

### Most Active Experts

1 Jeff@TargetTestPrep

Target Test Prep

134 posts
2 Brent@GMATPrepNow

GMAT Prep Now Teacher

131 posts
3 GMATGuruNY

The Princeton Review Teacher

130 posts
4 Rich.C@EMPOWERgma...

EMPOWERgmat

128 posts
5 Scott@TargetTestPrep

Target Test Prep

110 posts
See More Top Beat The GMAT Experts