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Q1. When your website conversion rate jumps from 10% to 12% then is it 2% rise in conversion rate or 20% rise in conversion rate? This question doesn't have a

by dkarl 14y ago

Q1. When your website conversion rate jumps from 10% to 12% then is it 2% rise in conversion rate or 20% rise in conversion rate? This question doesn't have a clear answer, because the values are already percentages. Imagine the original numbers refer to apples. First there were 10 apples, then 12 apples. The absolute increase is 2 apples; the relative increase is 20%. Obviously, if you say "the increase is __ apples" or "the increase is __ %" there's only one right way to replace the blanks with numbers. But since 10 and 12 are already percentages, the absolute and relative changes would be stated as "the increase is 2%" (absolute increase) and "the increase is 20%" (relative increase.) They mean different things, but they're both correct statements if interpreted correctly. In practice, people will expect one and interpret the other as wrong. Knowing which one they expect is not a matter of statistics.

pseut 14y ago
It's a change of two "percentage points," not 2%. With the right vocabulary, there's no ambiguity.
- dkarl 14y ago
  If you rely on people making the same precise distinction between "percent" and "percentage point" that you do, then you'll have more misunderstandings rather than fewer. It's like "next Friday." If today is Monday the 3rd and I say "next Friday," I don't rely on anyone outside my immediate family understanding that I mean Friday the 14th, since many people understand it to mean Friday the 7th.
  - pseut 14y ago
    I "rely" on the person saying that it went from 10% to 12%. I'll refer to such a change as a 2 percentage point change, but if the other person calls it the wrong thing, I don't really care. I'd be much more concerned about someone getting worked up about the semantics of the it and ignoring the context of the numbers. E.g. If they want to call it a 20% change and leave it at that, the misuse of terminology is the least of our problems. Witness: http://xkcd.com/1102/ http://xkcd.com/1102/
    - sctechie 14y ago
      Communication is at the heart of our problems. Your attitude is rather toxic. The xkcd you linked does little to soften your stance which appears to I don't care if the other person and I don't agree on terminology; to quote, "but if the other person calls it the wrong thing, I don't really care." There is REAL value in being able to communicate complex ideas effectively. In my opinion, agreeing on definitions for terminology is step #1 to having an effective conversation / discussion.
      - pseut 14y ago
        Look, this isn't a matter of "agreeing on the terminology." I know and use the correct terminology, but I don't get bent out of shape if the person I'm talking to doesn't know it. Especially when their mistake is obvious and I can correct for it in my head. I don't see how it is "toxic" to be lenient when talking to non-specialists who misuse terminology. By and large -- and, hey, you'll think this statement is toxic -- people who spend a lot of time worrying about whether something is called a "percent" or a "percentage point", outside the context of a classroom, do not know what they're talking about and have no business teaching anyone how to interpret statistics. Sometimes a change from 10% to 12% matters a lot. Sometimes it doesn't. Sometimes it would matter a lot, but is estimated so imprecisely as to be indistinguishable from noise. Sometimes it is measured very precisely but is meaningless. I could go on. This context-dependence is true whether you call it a percent, a percentage point, or just a "change." Most smart people understand this regardless of their statistical training. But then they read that, no, what really matters is what people call the change, and then they either 1) conclude that statisticians are pedantic morons who should be ignored and/or 2) psych themselves out and doubt their instincts and wind up worrying about trivial, trivial shit. Communication is important, but not the way you claim. It is important that specialists (be they statisticians, programmers, whatever) be able to explain things to clients/nonspecialists. It is also important that the specialists be able to interpret what the clients/nonspecialists want to understand and do. The burden falls entirely on the specialist, and any guide that spends any amount of effort to get nonspecialists to use the "correct" terminology is misguided and wasted at best. Which is what I meant by the "toxic" statement, "but if the other person calls it the wrong thing, I don't really care."

by dkarl 14y ago

pseut 14y ago

It's a change of two "percentage points," not 2%. With the right vocabulary, there's no ambiguity.

dkarl 14y ago
If you rely on people making the same precise distinction between "percent" and "percentage point" that you do, then you'll have more misunderstandings rather than fewer. It's like "next Friday." If today is Monday the 3rd and I say "next Friday," I don't rely on anyone outside my immediate family understanding that I mean Friday the 14th, since many people understand it to mean Friday the 7th.
- pseut 14y ago
  I "rely" on the person saying that it went from 10% to 12%. I'll refer to such a change as a 2 percentage point change, but if the other person calls it the wrong thing, I don't really care. I'd be much more concerned about someone getting worked up about the semantics of the it and ignoring the context of the numbers. E.g. If they want to call it a 20% change and leave it at that, the misuse of terminology is the least of our problems. Witness: http://xkcd.com/1102/ http://xkcd.com/1102/
  - sctechie 14y ago
    Communication is at the heart of our problems. Your attitude is rather toxic. The xkcd you linked does little to soften your stance which appears to I don't care if the other person and I don't agree on terminology; to quote, "but if the other person calls it the wrong thing, I don't really care." There is REAL value in being able to communicate complex ideas effectively. In my opinion, agreeing on definitions for terminology is step #1 to having an effective conversation / discussion.
    - pseut 14y ago
      Look, this isn't a matter of "agreeing on the terminology." I know and use the correct terminology, but I don't get bent out of shape if the person I'm talking to doesn't know it. Especially when their mistake is obvious and I can correct for it in my head. I don't see how it is "toxic" to be lenient when talking to non-specialists who misuse terminology. By and large -- and, hey, you'll think this statement is toxic -- people who spend a lot of time worrying about whether something is called a "percent" or a "percentage point", outside the context of a classroom, do not know what they're talking about and have no business teaching anyone how to interpret statistics. Sometimes a change from 10% to 12% matters a lot. Sometimes it doesn't. Sometimes it would matter a lot, but is estimated so imprecisely as to be indistinguishable from noise. Sometimes it is measured very precisely but is meaningless. I could go on. This context-dependence is true whether you call it a percent, a percentage point, or just a "change." Most smart people understand this regardless of their statistical training. But then they read that, no, what really matters is what people call the change, and then they either 1) conclude that statisticians are pedantic morons who should be ignored and/or 2) psych themselves out and doubt their instincts and wind up worrying about trivial, trivial shit. Communication is important, but not the way you claim. It is important that specialists (be they statisticians, programmers, whatever) be able to explain things to clients/nonspecialists. It is also important that the specialists be able to interpret what the clients/nonspecialists want to understand and do. The burden falls entirely on the specialist, and any guide that spends any amount of effort to get nonspecialists to use the "correct" terminology is misguided and wasted at best. Which is what I meant by the "toxic" statement, "but if the other person calls it the wrong thing, I don't really care."