Siebel Unleashed Poll Results

This a very interesting post. I'm not a statistician, but I wonder if the graphs contain as much information as you think they do.

In a voluntary poll such as this one, it is difficult to extrapolate the results beyond the sample. You can't actually say that most Siebel implementations are version 8.0 telephony implementations, although you can determine that most of the people who answered the poll say they are working on that type of implementation.

The one about the visitor's years of experience provides more reliable information, although it might not be representative of site visitors who didn't answer the poll (it is possible that more experienced professionals are less likely to answer the poll, for example).

The Years of Experience graph has a different problem: the groups are not the same size. You aren't comparing the same data. Even if the site visitors were distributed evenly by experience, so that 10% have < 1 year, 10% have < 2 years, 10% have < 3years, etc., the graph would look almost the same, because the first bar represents 1 year, the second bar represents 2 years, and the third bar represents 3 years. The fourth bar represents an unknown number of years, so we have to throw that one out.

To illustrate my point, imagine that the visitors who chose the 1-2 year bar were evenly divided, with half having 1 year and half having 2 years. Also imagine that the 3-5 years are divided evenly into thirds. Your results would look like this:

< 1 yr = 43 visitors
< 2 yr = 24 visitors
< 3 yr = 24 visitors
< 4 yr = 27 visitors
< 5 yr = 27 visitors
< 6 yr = 27 visitors

When you consider that the groups are probably not distributed as evenly as my hypothetical example above, as well as the other factor I mentioned earlier, about the survey not necessarily representing visitors who didn't answer the survey, and also consider that developers are like children when you ask them how old they are: "I'm going to be 4 next October", I don't think there is a significant difference between 24 and 27 visitors.