On Jun 15, 5:22*pm, "joeu2004" wrote:
"Onion Knight" wrote:
There has been some debate in COLA as to the correct way
to create a linear trendline in Excel. Someone in the forum
kindly made a video to show what he thought was the correct
method
http://tmp.gallopinginsanity.com/Lin...neCreation.mov
[....]
Does anyone see any missing steps for the creation of a
linear trend line?

I cannot find the original debate in comp.os.linux.advocacy (COLA); just the
thread titled "Visualizing where to draw the standard deviation line", which
refers to yet-another "a debate in COLA".

No matter; I'm not interested. *I think we can answer your Excel questions
without getting into anything so esoteric.

I see no missing steps in creating the linear trendline per se using Excel.

Given your reply it's pretty evident you realize that the process you
undertake depends on what your goal for creating the trend line is and
why you'd want to do the steps you mentioned in your reply. Earlier,
in another forum, Snit was talking about this and a poster cut right
to the chase by asking Snit (based on common sense and what Snit had
previously written) the two most obvious questions:

"I gather there are two questions he

1) Is the trendline approriately fitted to that data?

2) Is the trendline useful in some way?"

Snit's reply:
"Not quite: the question was merely if the process of creating the
trend line was correct - did it follow the process of creating a
linear trend line that is supported by the build in "linear trend
line" properties of the program."

As you can see, Snit himself explains that his goal was not to see if
the "trendline approriately fitted to that data" nor to have the
trendline be "useful in some way". Personally I find this rather
strange... but Snit's goal was revealed in the same post the above
quotes came from... and it's actually even more strange. Notably,
Snit wrote about a correlation between Linux UI improvements and an
increase in market share (a thing he has been arguing in another
newsgroup):

"The point, however, was not to predict the future past where I first
created the line. I had noted that the desktop Linux distros were
clearly focusing on improving their usability - and I predicted that
an increase in usability would lead to an increase in users."

And this, from the same post:

"But the graph was initially made to show that the then-current data
fit with my past predictions - not to make any specific prediction
about the future (such as that the same level of upward trend would be
seen)."


Anyone familiar with this topic knows that, regardless of the method
he used to create his "past predictions" (or any, for that matter) the
data Snit used would not aid in supporting a correlation between UI
improvements in Linux and a rise in marketshare because it's the wrong
kind of data.

We know Snit didn't care if the line fit his data or was useful in any
way... if he's going to argue that he didn't produce the line to show
evidence of his alleged correlation (a thing he is saying up above...
but possibly without realizing it) then one would have to logically
ask:

What the hell was the purpose of his trend line?