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Statistics course and homework discussion. Elementary statistics.enSat, 30 Aug 2014 07:36:07 GMTvBulletin60http://www.talkstats.com/images/misc/rss.pngStatistics Help @ Talk Stats Forum - Statistics
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What is the increase in sales? Percent of increase
http://www.talkstats.com/showthread.php/57425-What-is-the-increase-in-sales-Percent-of-increase?goto=newpost
Fri, 29 Aug 2014 12:24:39 GMTIf a bookstore sales is 200$ (x) per day, and after changing the manager, the sales became 800$ (y). Whats is the increase in sales and what does...If a bookstore sales is 200$ (x) per day, and after changing the manager, the sales became 800$ (y). Whats is the increase in sales and what does these 2 values represent?!

A = x/y = 800/200 = 400% increase

B = (x-y)/y = (800-200)/200 = 300% increase

Thanks!
]]>Statisticstnaserhttp://www.talkstats.com/showthread.php/57425-What-is-the-increase-in-sales-Percent-of-increaseComparing between subgroups of the population
http://www.talkstats.com/showthread.php/57416-Comparing-between-subgroups-of-the-population?goto=newpost
Thu, 28 Aug 2014 14:21:14 GMTGood afternoon,
Please I want your help.
If I am planning to compare between subgroups within my sample, shall I increase my sample size ? and...Good afternoon,

Please I want your help.

If I am planning to compare between subgroups within my sample, shall I increase my sample size ? and how ?

Regards and thanks in advance.
]]>StatisticsHadiRabeehttp://www.talkstats.com/showthread.php/57416-Comparing-between-subgroups-of-the-populationWhen to use derivation and validation cohort?
http://www.talkstats.com/showthread.php/57412-When-to-use-derivation-and-validation-cohort?goto=newpost
Thu, 28 Aug 2014 09:42:40 GMTHi everyone,

I was wondering if there is any generic rules on when it's good to use a derivation and validation cohort on a dataset? So far I have only seen them being used for diagnostic tests.

Also, if I use two datasets from two different studies to do this, do the datasets need to have the same primary endpoint? E.g. I am planning to do the derivation using one dataset and validation using another. The primary endpoint I am looking at is 30 days mortality for my research. One dataset records 30 days mortality, the other one only records in-hospital death within 30 days (if patients die after they are discharged, it is NOT recorded). Would it be correct to use one as validation and other as derivation cohort for this?

How do I actually apply the equation I have from derivation to the validation cohort? Is there any good book to read up on how to do derivation/validation?

Many thanks.
]]>Statisticsdubaifromhttp://www.talkstats.com/showthread.php/57412-When-to-use-derivation-and-validation-cohort