help please!

[khizarr]

can somebody please explain (i) what outliers are because i dont know how to analyse when given to calculate !
(ii) how do we analyse standard deviation values in a data?
thanks dor your cooperation .

 

[Zohaib Sherazi]

Outliers are "extreme" values that do not generally fit the trend of the given data. For example, assume a data set: 10,11,12,13,14,15,16,17,74. Did you notice the outlier? Yes, its 74. Assume further that the question asked you to calculate the median. As the data is already arranged in ascending order the median will be 14. Whatever the outlier the median will not be affected. But when you take the mean of the data set you will see that the outlier has a huge impact on the answer. So, we have to exclude outliers when calculating the mean.

Standard deviation shows you the spread of data around the mean. Assume again that a data set has a mean 12 and S.D 4. We can therefore get to know that 95% of our values will be in the range 8-16. i.e. 12+4 =16 and 12- 4 = 8. Doing this increases the reliability of our calculation. (remember reliability and not accuracy).

 

[khizarr]

oh! thanks a gazillion! i never knew about excluding outliers when calculating mean and also thank you for S.D !! thanks zohaib!

 

[alisha]

duz any1 knw hw i get physics o/l markschemes? im soo lost!

 

[PlanetMaster]

Go to www.xtremepapers.net. Go to CIE, your level and then your required subject.
You'll get a long list of resources for that subject.
If you are unfamiliar with those file codes, please see http://www.xtremepapers.net/guide.html

 

[BEHRAM AHMED]

please help me what to do now . past papers or revision of syllabus?

 

[Zohaib Sherazi]

If its mcqs then past papers. If its theory, revise key points

 

[alisha]

syllabus then pastpapers then revision!