Talk:Weighted mean

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[edit] Merge Convex combination into Weighted mean?

Convex combinations and weighted means are, on a fundamental level, precisely the same things. The major difference between them seems to be the way they are written. In a weighted sum, a normalizing factor is written outside the sum sign; in a convex combination, it is absorbed into the coefficients, which then sum to 1. Is this notational distinction a big enough deal to warrant separate articles? Melchoir 02:12, 19 April 2006 (UTC)

While I wait, I'll add these articles to each others' categories. Melchoir 02:13, 19 April 2006 (UTC)

It sounds to me like a "convex combination" is an application of the weighted mean. If this is true, it should contain a link to the weighted mean article for examples on how to do the calculations, but should remain a separate article (since the average person reading about the weighted mean will have absolutely no interest in the "convex combination" application). StuRat 03:51, 19 April 2006 (UTC)

Actually, the more I think about it, the more I think they should stay separate. Partly because of the reasons you bring up, and partly because the formalism can actually be important at times. Well, I'll remove the tags in a bit if no one else speaks up. Thanks for commenting! Melchoir 06:14, 19 April 2006 (UTC)

You're welcome. StuRat 21:15, 19 April 2006 (UTC)

...done. Melchoir 08:44, 30 April 2006 (UTC)

[edit] Confusing Lead Sentance?

"The weighted mean, or weighted average, of a non-empty list of data

with corresponding non-negative weights

at least one of which is positive, is..."

So at least one of which is positive? I assume it can't be the weights, since they are stated to always be non-negative, is it the data that always has to be positive, and why is that the case? CallipygianSchoolGirl (talk) 15:15, 21 January 2008 (UTC)

It is the weights. There is a small difference between nonnegative and positive: zero is nonnegative but it is not positive. So what the text says is that not all the weights can be zero. However, it is a bit confusing so I reformulated it. -- Jitse Niesen (talk) 17:13, 21 January 2008 (UTC)