SpreadEveryone: The Fetchland Excel wire

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GregP Sep 2019 1:59pm, 18 Sep 2019 114,885 posts	0 GregP That's not a particularly numpty question I don't think.
flanker Sep 2019 2:07pm, 18 Sep 2019 18,581 posts	0 flanker You don't need a SD to plot a bell curve, assuming you mean a normal distribution curve - the curve can be used to derive the SD. Not sure I understand what you're looking to achieve? The bell curve is an outcome of a set of data if it follows a normalised distribution - if it doesn't the volume of data is irrelevant.
macca 53 Sep 2019 2:10pm, 18 Sep 2019 27,031 posts	0 macca 53 Even more specifically could it be done from knowing the mean (range) and % range values at either end of the range.? For example if something has a mean value of 50-65 and >85% have a value below 125. If mean is 50 then no more than 70% of values are <63 and if mean is 65, no more than 40% of values are <63
macca 53 Sep 2019 2:10pm, 18 Sep 2019 27,032 posts	0 macca 53 Numpty enough?
Neal Sep 2019 3:34pm, 18 Sep 2019 94 posts	0 Neal I'm not very good at statistics, but if it helps, you can use Excel to calculate the required standard deviation using NORM.DIST and goal seek. So if the mean of your normally idstributed data is 50 and 70% are less than 63, it seems your standard deviation is 24.7ish.
flanker Sep 2019 5:58pm, 18 Sep 2019 18,582 posts	0 flanker I think, as i'm still confused, the answer is yes if you know the data is normally distributed, otherwise no. I've never played with goal seek. Probably because I like to be able to tell where a number came from
macca 53 Sep 2019 5:59pm, 18 Sep 2019 27,034 posts	0 macca 53 thanks Neal, that might be enough to help!
GlennR Sep 2019 6:09pm, 18 Sep 2019 45,040 posts	0 GlennR Can’t do internal rate of return without goal seek flanker, even if you can’t see it doing it.
SPR Sep 2019 7:09pm, 18 Sep 2019 29,296 posts	0 SPR That's the one and only time I've used goal seek Glenn.
GlennR Sep 2019 7:20pm, 18 Sep 2019 45,045 posts	0 GlennR We use it quite a lot in the project finance/option appraisal world, trying to establish price for a given level of profit, for example. Recursive algorithms are important for quite a lot of mathematics. You could try Gödel, Escher, Bach, an Eternal Golden Braid, if you fancy some light background reading. ~cough~ A client of mine uses a recursive algorithm and fractal geometry for cytology applications.