Possible Error in Graded Assignment 3 Question 14

[Ashish Verma]

Hi,

    In question 14 of week graded assignment 3 , you have marked the first option as correct. 

But according to definition of percentiles, a sample 100p percentile has 100(1-p) percent of data values greater than or equal to it.

In this question, we cannot be sure that 30% of people are taller than me. It is possible that they all are as same height as me. You have missed this small detail while framing the question.

I have attached the screenshot of the question below.

So please recheck it and provide me an explanation.

[Abhishek Kumar]

I was also confused....but the thing is 30% of people are taller than you is also correct or 30% people are taller or same height as you is also correct. The statement is not wrong, the or thing doesn't make the first statement incorrect.

[Abhijeet Gope]

When we say OR, either is true.

When we say AND, both are true.

In isolation also, both conditions are true (in case of AND).

BUT, in case of OR, in isolation, it would be wrong to hail any one statement as true.

Would appreciate it if course instructors clarify this.

[Ashish Verma]

NO, it is not.

Consider this hypothetical dataset of 10 observations.

    1 2 3 4 5 6 8 8 8 8

Let your height be the bolded 7th observation i.e., 8.

If I say that 30% of people in dataset are taller than you, will it be correct?

Answer : NO

Because no person is taller than you.

The assumption you have taken that all observations in dataset are different is wrong.

The question has not asked "Which among the following options CAN BE correct?"    (high probability answer)

It has asked "Which among the following options IS/ARE correct?"   (100% correct answer)

I hope this clears things up for you

On Tuesday, November 3, 2020 at 11:37:41 AM UTC+5:30 abhin...@gmail.com wrote:

[Abhijeet Gope]

Exactly.

If I am at the 70th percentile, 30% of people are taller than or the same height as me.The heights of all 18 people in the group can very well be the same, in that case how can the statement "30% of people are taller than you" be right. 30% of people can also be the same height as me.

Alternatively, if I am at the 70th percentile in group of 18 people, I am the 13th ranked person. What if the 14th and the 15th ranked persons are the same height as me and the 16th, 17th and 18th rank holders are taller.

It is very wrong to say that "30% of people are taller than you", in my opinion.

[prav...@gmail.com]

Completely agree.

The formal definition of percentile specifies the equality sign on either side (GE 100p, LE 100(1-p)).

So statement that 30% are taller is incorrect.

Only option C (GE 70%) can be correct

Best,

Praveen

[Statistics 1 Support 1]

Hello, 

We will be awarding marks to everyone for question 14.

Thanks & Regards,

Ram,

Course Support Team

[Arun kumar N]

Hi,

I need clarification on option number 2 here. "30% of the people are shorter than you". Why is this statement not correct? If 70% of the people are shorter or the same height as you, then x% of people are shorter than you where 0<=x<=70, right? In my opinion, statement 2 should be correct. However there is no way statement 4 is correct. Please let me know what you think.

Regards,

Arun

[Statistics 1 Support 1]

Hello,

Option 2 is also correct. We are awarding marks to everyone for this question.

Thanks & Regards,
Ram,

Course Support Team

[Abhijeet Gope]

Hi!

How can option "30% of the people are shorter than you" be correct? Again, it should be 30% of the people are shorter than or the same height as yo, even if we are applying the logic suggested above.

Regards

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