Tuesday, March 27, 2012

Simple manipulation of statistics


We show by example. Take the profit figures kazapy for the entire period of existence. No traffic, namely profit, in order, from which then goes into his pocket and the division of paid salaries and rent, r. e. as a system of earning money. And trying to find some regularity in the dynamics of.






Schedule of revenue growth from month to month is not impressive. This is me as a specialist, he says something ( even though the system fluctuates at a profit, but growing). However, this does not impress the layman. He needs a nice plot with beautiful figures. Moreover, that this graph is a vulnerability: it does not take into account seasonality, as well as discrete, so the two adjacent months may differ in their performance.






Graph comparing with last year is much better. One negative - need to explain why such a small gain in January. But the schedule does not stick the guide to explain that the purchase is discrete, and in early 2011, a single customer has made a particularly large purchase options, which could cut off in January next year, only 20%. But this is a start-up. Therefore, we construct another graph.







And now, even though the schedule and the uneven, there is still a clear rise. What kind of schedule? . This schedule will surely love the man in the street, and most importantly, it is absolutely truthful, as profit for the year grew about twice as. Although the only thing that can be computed on it, and understand is the growth rate from month to month from the slope of the straight line connecting two adjacent points. More can be said that the profits grew, first rapidly, then not, then again quickly. But it 's all that can be squeezed from this graph, but looks nice.

It is not always rough schedule - it's bad, but it will be able to read correctly only a few, so the public is full of statistics of smooth curves and diagrams, which give a little to understand what the situation.

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