Comments on: Estimating Sales, Part III: Converting Amazon Sales Ranks into Sales Estimates http://gropenassoc.com/blog/2009/02/estimating-sales-part-iii-converting-amazon-sales-ranks-into-sales-estimates/ Discussion, issues and answers for the independent publishing community, hosted by Marion Gropen Thu, 05 Apr 2012 12:57:28 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Estimating Sales, Part V: A Technical Issue « The Profitable Publisher http://gropenassoc.com/blog/2009/02/estimating-sales-part-iii-converting-amazon-sales-ranks-into-sales-estimates/comment-page-1/#comment-17024 Estimating Sales, Part V: A Technical Issue « The Profitable Publisher Thu, 04 Nov 2010 12:27:22 +0000 http://gropenassoc.com/blog/?p=66#comment-17024 [...] commenter on Estimating Sales, Part III was having difficulty with the logarithmic nature of that graph. So, rather than answer the [...] [...] commenter on Estimating Sales, Part III was having difficulty with the logarithmic nature of that graph. So, rather than answer the [...]

]]> By: Marion Gropen http://gropenassoc.com/blog/2009/02/estimating-sales-part-iii-converting-amazon-sales-ranks-into-sales-estimates/comment-page-1/#comment-17023 Marion Gropen Thu, 04 Nov 2010 12:01:06 +0000 http://gropenassoc.com/blog/?p=66#comment-17023 Thank you for commenting, David. I overlooked the fact that not everyone knows how to use a logarithmic scale. I'm going to do a post on that issue, right now. Thank you for commenting, David. I overlooked the fact that not everyone knows how to use a logarithmic scale. I’m going to do a post on that issue, right now.

]]> By: David http://gropenassoc.com/blog/2009/02/estimating-sales-part-iii-converting-amazon-sales-ranks-into-sales-estimates/comment-page-1/#comment-17021 David Thu, 04 Nov 2010 03:38:59 +0000 http://gropenassoc.com/blog/?p=66#comment-17021 Ive been studying that chart on foner books for a while now. As Im trying to come up with the right formula to convert the sales rank into a books sold per week number. Now I understand its logarithmic... but the chart dosnt make sense to me. Because the lines are uneven on both axis of the chart. Each range is divided by 10, thats for both axis. So do you take half way to be line 5? Or do you take half way to be half the physical measure along the axis? The reason I ask (Im no mathematician) is because if you use the uneven lines to find the related number on the other axis... theres no point in having it logarithmic at all. It defeats the point. The chart in order to be correct should be even on one axis. My guess has always been, that it must be and that the lines are supposed to help you estimate the number your after... but, which axis is even, which is not. The chart is not very well explained. Ive been studying that chart on foner books for a while now. As Im trying to come up with the right formula to convert the sales rank into a books sold per week number.

Now I understand its logarithmic… but the chart dosnt make sense to me. Because the lines are uneven on both axis of the chart.

Each range is divided by 10, thats for both axis. So do you take half way to be line 5? Or do you take half way to be half the physical measure along the axis?

The reason I ask (Im no mathematician) is because if you use the uneven lines to find the related number on the other axis… theres no point in having it logarithmic at all. It defeats the point. The chart in order to be correct should be even on one axis.

My guess has always been, that it must be and that the lines are supposed to help you estimate the number your after… but, which axis is even, which is not.

The chart is not very well explained.

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