Comments on: Modeling market adoption in Excel with a simplified s-curve

By: sridhar

sridhar — Mon, 02 Aug 2010 00:36:47 +0000

If we sum the penetration – are we supposed to get 1 – to represent 100% ?
i am getting 2 plus

By: mhde

mhde — Sun, 25 Apr 2010 14:23:07 +0000

Dear Sir,
Thanks for the usful information I read about Rogers theory, that you provided, and I need your kind help in the following: Im trying to use Rogers diffusion of innovations theory in my research study which is: the adoption of e-procurement system innovation in the public sector. I need your kind advice to let me know:
1.Do you think I can implement or use Rogers’s theory in this area?
2.is there any scale or model in Rogers that I can use to apply it in my subject? Where can I find it? I mean how I can apply Rogers’s theory in my research in a practical way?

Regards and many thank for your time, hope I can have help and advice from you [I really need it], or if you know some one who can advice me?
Have a good day

By: Renny

Renny — Sat, 27 Mar 2010 19:27:48 +0000

Good morning

Thank you for your post, however, it seems that the link is broken. I can´t entered, or downloaded the file. Would you mind to fix it?

Thank you again

Renny

By: Kevin

Kevin — Mon, 25 May 2009 02:15:51 +0000

Um…
Excuse me. I have a problem.
How to use the simplified formula in Excel?
Cause I have try various way, but I can't draw S-Curve.
Could you send me an example?xls? to my e-mail ?
Thank you so much.

By: Ben Grimes

Ben Grimes — Wed, 25 Mar 2009 23:51:04 +0000

Hi Juan
Interesting webpost about sigmoid curves, It’s exactly what I’m looking at at the moment, modelling the take up of doordrop coupons for various products.
Only thing is i couldn’t download your excel spreadsheet to see what you’re doing exactly which would be interesting.
Can you please advise

sincerely
Ben

By: John

John — Wed, 25 Feb 2009 23:11:21 +0000

Hi Juan,

I wondered if you still had the example spreadsheet? I’d really like to see this in action.

By: Juan Carlos Méndez-García

Juan Carlos Méndez-García — Thu, 05 Feb 2009 08:44:20 +0000

@Mark

You can use different sets of parameters for each of your products. Then, set the hypergrowth and takeover accordingly. Lets say you have prod1 and prod2. So you define the formulas for each using different parameters (i.e. hypergrowth1, takeover1 and hypergrowth 2 and takeover 2). So if prod2 launches 5 years after prod1, you set the value for takeover2 to takeover1+5. When modeling more than one product, think how you will incorporate interactions between them (i.e. is prod2 the next generation of prod1, are they substitutes, complementary or independent, etc.)

By: Mark Woodward

Mark Woodward — Wed, 04 Feb 2009 17:08:14 +0000

Hi Juan
First off, thanks so much for this. Even i (a total non-modeller) have been able to create the s-curve using your formula.
I also need to model different products launching at different times and wondered how the base year (month) could be used in the equation to allow this? Apols if this question is not clear!
Mark

By: PicoBusiness » nice sigmoid function

PicoBusiness » nice sigmoid function — Sun, 11 Jan 2009 15:01:10 +0000

[...] This is handy, if you need to produce S-curves in Excel [...]

By: Logistic model for the s-curve and project management cost estimation | Juan Carlos Méndez-García

Sun, 21 Dec 2008 04:51:54 +0000

[...] posted a while ago an article on Modeling market adoption with a logistic curve in Excel. It has been quite popular on this site, and even at some point was linked as a reference on [...]

By: Juan Carlos Méndez-García

Juan Carlos Méndez-García — Fri, 05 Dec 2008 15:37:32 +0000

@Benedict

Thank you for the message. I would recommend one of these approaches based on the info you have available, and your particular needs:

(1) estimate by analogy to other historic records of adoption, and perform subsequent refinement (i.e., visual tracking). This requires finding a similar case of adoption (i.e. fax, personal computer, teletype, iPhone, etc.) to use as your reference. For Bass model, you may find p (innovation) and q (imitation) for several industries and products. As a rule of thumb if I don’t have data, I start with p=0.02 and q=0.4 – I think Mahajan, Muller, and Bass (1995) has some listed p and q

(2) fit the logistic or Bass model to past data using nonlinear least squares. Look up Srinivasan and Mason (1986). This is tricky for very early stages of innovation, as there may be huge variability on the “end game” for small variations in your estimated parameters.

Hopefully this points you in the right direction

By: Benedict

Benedict — Fri, 05 Dec 2008 14:55:35 +0000

A late followup question: what do you do when adoption has already started? WHat happened is you already have the real data through to, say, 2007 in your example above? Is there a way to fill in the rest of the S curve adapting to the existing data run? There ought to be a way to drive the variables from the historic data, but I can’t quite work out how…

By: Debbie

Debbie — Thu, 24 Jul 2008 13:57:13 +0000

Hi Juan,
Thanks for providing this example. It’s very useful! What I would like to do, however, is to find the gradients of the S-Curve at any desired point. How would I find that using excel, after my Curve has been created?
Thanks!

By: Tim Snijder

Tim Snijder — Thu, 26 Jun 2008 07:42:05 +0000

Thanks a lot for the great example. I want to create an s-curve that I can use to estimate the effects of marketing expenditures on sales. I know that normally this should be based on transaction data. In this case, I don’t have this data so I just want to create a curve where I manually enter saturation levels and base sales (number of sales generated without any marketing expenditures)
Does anybody have an idea how to apply this?

By: Billy

Billy — Wed, 25 Jun 2008 13:29:39 +0000

Hi Juan,
I like the way you have rephrased the parameters of the model to useful inputs that people can work with. I use the Bass curve in new product forecasting using an interactive dashboard to get everyone involved in the ‘what if’ sensitivity analysis process. There is a link to it on my blog page http://acasoanalytics.wordpress.com/2008/06/25/interactive-bass-diffusion-model/ . I’ll have a go at doing the same with your approach.

By: Mathias

Mathias — Mon, 09 Jun 2008 00:01:36 +0000

Hi Juan, Thanks for your series on the S-Curve, which was most helpful. I needed to be able to specify a curve through any pair of values, and not just 10%/90%, and resolved that question here, in case you are interested. While more flexible, the formula I end up with is also way more complicated / painful, and I would therefore recommend that people stick with yours in general, as it is much more compact and readable!

By: S-shaped market adoption curve

S-shaped market adoption curve — Sun, 08 Jun 2008 20:20:41 +0000

[...] products entering the market would follow a S-curve. After some digging and googling, I came across this excellent post by Juan C. Mendez, where he proposes a clean and very practical way to use the logistic function, and calibrate it [...]

By: Ryan

Ryan — Fri, 16 May 2008 19:31:17 +0000

If you want a generalizable way to specify the penetration level before the hypergrowth starts, you can add a variable “Penetration Level Before Hypergrowth” and use this instead of 81:

((saturation/penetration_before_hypergrowth)-1)^2

In the example above, penetration reaches 3% (or 10% of the 30% saturation) before hypergrowth, so:

(( 30% / 3% ) – 1) ^ 2 = 9 ^ 2 = 81

Cheers,
Ryan

By: Ider

Ider — Mon, 28 Apr 2008 11:44:35 +0000

Hello Juan,
I also want to express my grattitute
Could you explain me about how (in what extent) is it reliable to consider that behaviour of the curve before and after hypergrowth period is same in real business. In other words, in real business can we believe that growth size before and after hypergrowth would be same?
Sorry for my poor English if I couldn’t express my question.
Thank you!

By: Juan C. Mendez

Juan C. Mendez — Fri, 07 Mar 2008 03:12:29 +0000

Phil

Thank you for your message. The modified formula, as you would like to use it would be

=initial_adoption + (saturation-initial_adoption)/(1+81^((hypergrowth+takeover/2-year)/takeover))

Hope it helps!

By: PhilT

PhilT — Thu, 06 Mar 2008 09:48:18 +0000

Hello Juan,

Many thanks for providing a great and comprehensible work around for lpeople (like me) wanting to utilize s curves in an excel model, without really understanding the maths behind it. Could you possibly spell out in idiot proof terms (the idiot being yours truly), the full formula with the ‘initial adoption’ parameter added as per Pushkars mail. It would be greatly appreciated. Thanks, Phil.

By: Juan C. Mendez’s pages » Blog Archive » System dynamics interpretation of the logistic and Bass models

Fri, 21 Dec 2007 19:42:30 +0000

[...] have received a number of comments regarding the Simplified Excel Model for market adoption that I published a few months ago. Reader Vince asked how to extend the math behind it to [...]

By: Juan C. Mendez

Juan C. Mendez — Thu, 01 Nov 2007 02:58:10 +0000

@Donald, @Kevin I just posted a screencast that should help with your questions

By: Kevin

Kevin — Sat, 20 Oct 2007 07:51:21 +0000

Um…
Excuse me. I have a problem.
How to use the simplified formula in Excel?
Cause I have try various way, but I can’t draw S-Curve.
Could you send me an example?xls? to my e-mail ?
Thank you so much.

By: Donald

Donald — Wed, 19 Sep 2007 17:04:33 +0000

Juan,
I cannot see the formula you have pasted in cel B8.
Where can I find it, if I am may ask?