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Math Help - Need a term for a trend

  1. #1
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    Need a term for a trend

    Sorry, this is a basic question. I'm looking for a term which describes the following kind of trend.

    Let's say a value in a time series peaks at a rate of 100 in the third year. The rates during the build-up phase are 50 in Year 2 and 25 in Year 1. In other words, during the build-up up to and including the first year of the peak, a predecessor is always half of its successor.

    I'd be grateful for any help.
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  2. #2
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    Quote Originally Posted by lingyai View Post
    Sorry, this is a basic question. I'm looking for a term which describes the following kind of trend.

    Let's say a value in a time series peaks at a rate of 100 in the third year. The rates during the build-up phase are 50 in Year 2 and 25 in Year 1. In other words, during the build-up up to and including the first year of the peak, a predecessor is always half of its successor.

    I'd be grateful for any help.
    Exponential trend or growth

    RonL
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  3. #3
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    Thanks. But is there a way to describe this trend of doubling rates up to and including the build-up have a special name -- in other words, is there a more succinct way to describe it than in my original post?
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  4. #4
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    Quote Originally Posted by lingyai View Post
    Thanks. But is there a way to describe this trend of doubling rates up to and including the build-up have a special name -- in other words, is there a more succinct way to describe it than in my original post?
    Exponential growth with a doubling period of 1 year from an initial value of 25.

    RonL
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  5. #5
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    Quote Originally Posted by lingyai View Post
    Sorry, this is a basic question. I'm looking for a term which describes the following kind of trend.

    Let's say a value in a time series peaks at a rate of 100 in the third year. The rates during the build-up phase are 50 in Year 2 and 25 in Year 1. In other words, during the build-up up to and including the first year of the peak, a predecessor is always half of its successor.

    I'd be grateful for any help.
    Geometric progression. Or, geometric sequence.

    The common ratio between two progressing, successive terms is 2.
    y1 = 25
    y2 = 50
    y3 = 100
    .
    .

    ---------------
    y2/y1 = 50/25 = 2
    y3/y2 = 100/50 = 2
    .
    .
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