[RkWard-devel] Pareto chart and Quality qontrol charts

[Thomas Friedrichsmeier]

On Friday 23 February 2007 21:21, I. Soumpasis wrote:
> I disagree here because of the meaning of the data. Pareto chart is used
> when you have data like this
> A B C D E F
> 1 1 1 2 2 3
> Suppose that the above is type of defects, you can take the pareto chart
> with the most serious of them. It has a different approach of the barplot.
> The summary(factor) gives the the factor variable in this way to help the
> user not to have to make a new variable in order to use the plugin.

True, but summary (factor) is essentially identical to table (factor). (More 
precisely: table (factor, exclude=NULL) to keep the NAs, so that would be 
more correct).

> But the pareto.chart (and the plugin) is meaningless for
> a <- rep (c (1, 1, 1, 2, 2, 3), length.out=100)

But what if 1, 2 and 3 are actually three different types of failures (and the 
user simply didn't define this as a factor)? Or a count of defects on a 
single unit (perhaps pixel errors on an LCD, and the defect count influences 
the sale category), so it's actually reasonable to store in a vector instead 
of a factor? In these cases, table sums them up nicely, as:

> table (a)
a
 1  2  3 
51 33 16 

> If these are the names the user must make them factor  so to make a
> pareto.chart() and use the plugin.

The question I'm having is this:
Are there any vectors (not factors, and not tables) that could meaningfully be 
displayed as raw data? If not, then either the plugin should not accept 
vectors at all, or it should convert them to something that it can display in 
a meaningful way. If there are, then it may still be worth considering, 
whether the type of data I suggested should not be supported in some way as 
well, perhaps with a "tabulate" option.

Regards
Thomas
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