For each of 7 models of mobile telephone, the table shows the phone's

Question

For each of 7 models of mobile telephone, the table shows the phone's thickness, screen size, display surface material, battery life, and whether that phone has Internet capabilities. Model Thickness (mm) Screen size (mm) Display surface Battery life (hours) Internet capable? A 11.6 85 glass 9 yes B 21.0 80 glass 9 yes C 11.7 78 glass 10 no D 15.5 88 plastic 4 no E 22.0 82 plastic 8 yes F 14.0 85 plastic 6 no G 18.0 85 plastic 6 yes For each of the following statements, select Yes if that statement accurately reflects the information provided. Otherwise, select No. https://gmatclub.com/forum/download/file.php?mode=view&id=73354 Table.png

vmn2007 · Answer

-  Screen size is negatively correlated with battery life  -> Broadly we can say a negative correlation, but there is one datapoint which is an anomaly. In these cases, how should we mark the answer.

MartyMurray · Answer

Since, in all cases but one, screen size is negatively correlated with battery life, we can choose Yes for the first statement since it's true that, in general, screen size is negatively correlated with battery life.

In general, when the vast majority of the data points in two categories in a table are correlated or negatively correlated, even though a data point or two don't fit the pattern, we can say that the data points in the two categories are correlated or negatively correlated.

AnkurGMAT20 · Answer

MartyMurray  but I have seen different questions in DI, where such a assumption was marked wrong because it asked for specific answer. In this case and other table questions, usually we see that even if one data point is different, we tend to go the other way. Not 100% convinced why this is the right answer.

GMATCoachBen · Answer

AnkurGMAT20  I agree with  MartyMurray . What I've seen on the GMAT (as well as the real-life definition) is that "negatively correlated" just means a general trend of the vast majority of data points. There can be a data point that's an exception to the trend, and there is still a correlation.

It sounds like you believe there are counter-examples? I'm very curious, are there any specific examples from official questions you could link to? Thanks!

sayan640 · Answer

Here is that example GMATCoachBen GMATinsight
Q2 :- https://gmatclub.com/forum/the-table-gives-information-about-teacher-absenteeism-in-21-school-430451.html#p3407184

Kindly check the link. The majority concept for determining the correlation does not follow in this case. MartyMurray

GMATCoachBen · Answer

Hi sayan640 , this is not a counter-example. There is not a positive correlation ( a positive correlation must have a positively sloped trend line ); if we sort by "number of teachers", the "average days absent" data are all over the place. I've also had GPT-4 create a graph below. https://gmatclub.com/forum/download/file.php?id=82262 https://gmatclub.com/forum/download/file.php?id=82263 https://gmatclub.com/forum/download/file.php?id=82264 GMAT-Club-Forum-r0gcsj18.png GMAT-Club-Forum-wsugm81s.png GMAT-Club-Forum-wdj7mi85.png

pratiksha1998 · Answer

GMATCoachBen  Is there any specific limit to the corelation point? For Example:- If there are 10 items in a table and 6(more than 50%) show a positive trend then we have to consider it a positive correlation?

Ankit__7182 · Answer

There's no limit as such but the values should follow a slope line (either positve or negative) https://gmatclub.com/forum/download/file.php?id=82463 GMAT-Club-Forum-d1s1xijl.png

dhruva09 · Answer

Bunuel  Can you please confirm, if in Q1, we need to go about, if over 50% of the data follows a certain co-relation, then that is to be considered. Model A does not follow the pattern.

Bunuel · Answer

You do not use a “more than 50 percent” rule for correlation questions or any other arbitrary threshold. Correlation is about the  overall direction  of the relationship across the full set of data points, not about whether every single data point follows the pattern. It is normal to have an exception like Model A in this question and still have a negative overall trend. Here, as screen size increases from 78 to 88, battery life  generally  follows the opposite trend and decreases from 10 to 4, so we have a negative correlation. The correlation for these two data sets is about -0.85 ( you do  not  need to know how to calculate this for the GMAT ), which is a  strong negative correlation , even though there is an exception in the pattern.

Yes	No
		Screen size is negatively correlated with battery life.
		All phones with a glass display are Internet capable.
		The thickest phone has the least battery life.

For each of 7 models of mobile telephone, the table shows the phone's

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

Model	Thickness (mm)	Screen size (mm)	Display surface	Battery life (hours)	Internet capable?
A	11.6	85	glass	9	yes
B	21.0	80	glass	9	yes
C	11.7	78	glass	10	no
D	15.5	88	plastic	4	no
E	22.0	82	plastic	8	yes
F	14.0	85	plastic	6	no
G	18.0	85	plastic	6	yes

GMAT Graphs and Tables (G&T) Questions

For each of 7 models of mobile telephone, the table shows the phone's

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards