# How is this graph NEGATIVELY SKEWED

1. Jan 4, 2012

### jsmith613

1. The problem statement, all variables and given/known data
http://www.thestudentroom.co.uk/attachment.php?attachmentid=103146&d=1306479703

Look at question 3(d)
and the graph for question 3
how is this graph NEGATIVELY SKEWED

2. Relevant equations

3. The attempt at a solution
I know that a -ve skew has a tail in the low x-values but I find it difficult to see that here :(

(I am not sure what further attempt I can give, I have said everything I know about shapes of skewed curves I just cannot see why it is -ve. I was hoping someone could help me with this!)

2. Jan 4, 2012

### rollcast

Re: Skewness

Look at the answer to part c, a = 5.

So the left tail is 3 units long and the right tail is 2 units long

3. Jan 4, 2012

### jsmith613

Re: Skewness

I always though the tail was a flat bit? how does the tail relate to the median / mode
is it as follows:
the mode is assumed to be the middle of the graph
if the a<x<mode is greater than mode<x<b for a graph a<x<b then it is negative skew
if a<x<mode is less than mode<x<b then the graph for a<x<b is +ive skew?

4. Jan 4, 2012

### rollcast

Re: Skewness

Sorry I was in the wrong part of my book for the answer, ok not much help but my book says

Negative skew = Mean < Median < Mode.

Positive skew = Mean > Median > Mode.

5. Jan 4, 2012

### rollcast

Re: Skewness

Then you can deduce that because the area of both sides of the mode is the same, then the mean will lie on the longer side.

6. Jan 4, 2012

Re: Skewness

oh I see
ok
thanks