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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: Cel126 on February 14, 2013, 11:53:34 am

Title: Centre (middle) of a skewed histogram
Post by: Cel126 on February 14, 2013, 11:53:34 am
Hey Guys,
I was just going over some statistics work and I wasn't 100% sure on how to find the centre (middle) of a a skewed histogram (either positive or neg).  I was told by someone that you have to estimate, or is there a particular way?
thanks  :)
 
Title: Re: Centre (middle) of a skewed histogram
Post by: REBORN on February 14, 2013, 11:54:48 am
Graphically? It's just a rough estimate. The centre will be closer to the skewed side!
Title: Re: Centre (middle) of a skewed histogram
Post by: Cel126 on February 14, 2013, 01:46:04 pm
Graphically? It's just a rough estimate. The centre will be closer to the skewed side!

Yes Graphically, okay thanks for that ! :)
Title: Re: Centre (middle) of a skewed histogram
Post by: Daenerys Targaryen on February 14, 2013, 02:01:34 pm
I don't exactly remember, but I'm pretty sure I use to add up all of the entries. Divide by how many there where. That would give me the middle number of entry. Then I'd count that many entries from left to right (or which ever way) and what ever value that entry had would be the centre.
Title: Re: Centre (middle) of a skewed histogram
Post by: Stick on February 14, 2013, 06:05:53 pm
Hey Guys,
I was just going over some statistics work and I wasn't 100% sure on how to find the centre (middle) of a a skewed histogram (either positive or neg).  I was told by someone that you have to estimate, or is there a particular way?
thanks  :)
 

Use the median, if it's possible. :)
Title: Re: Centre (middle) of a skewed histogram
Post by: Daenerys Targaryen on February 14, 2013, 06:08:03 pm
Right - that's what I was explaining. Lol.
Title: Re: Centre (middle) of a skewed histogram
Post by: REBORN on February 14, 2013, 09:36:54 pm
Yeah...the median is a numerical measure. My answer is graphical.

If the y-axis is in percentages, the centre is given by the bar at 50% (median by definition)
Title: Re: Centre (middle) of a skewed histogram
Post by: Daenerys Targaryen on February 14, 2013, 09:51:06 pm
Also note that with symmetrically shaped graphs, mean is the best measure of the middle
However when it's skewed median is the best.
Title: Re: Centre (middle) of a skewed histogram
Post by: Yacoubb on February 15, 2013, 07:29:18 am
Find the Median of the distribution using the (n+1/2)th position rule. After locating the position of the median, count through the frequencies until you get to an approximate of that; that would be your median interval :)
Title: Re: Centre (middle) of a skewed histogram
Post by: Cel126 on February 16, 2013, 11:41:03 am
Thanks for the help everyone :)