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Thread: Use for sampling

  1. #1
    Join Date
    Jun 2007
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    Default [Solved] Use for sampling

    As part of an audit being conducted, I need to select a sample from a given population.

    Would I be able to use Kettle for this task (or is this more a data mining function)?

    Here is a broad (and incomplete) list of my requirements :
    • The initial population may be subjected to filtering - for example, all amounts less that (say) 10 00 will be excluded from consideration.
    • I may need to choose either a simple (random) sample or a stratified sampling.
    • I will have to provide the required sample size
    Thank you
    Pradesh
    Last edited by crafter; 12-12-2007 at 07:33 PM.

  2. #2
    Join Date
    Jun 2007
    Posts
    260

    Default

    Found this thread related to this topic:
    http://forums.pentaho.org/showthread...light=sampling

    For audit purposes, the randomness of the sample selction is important, and any kind of ordering will be deemed too predictive of the sample.

  3. #3
    Join Date
    Nov 1999
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    9,729

  4. #4
    Join Date
    Jun 2007
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    Default

    Reservoir Sampling is eactly what I need. It's missing stratified sampling, but should cater for mots of my needs.

    For those too lazy to download,, here is the first line of the user doc.
    The reservoir sampling plugin is a tool that allows you to sample a fixed number of rows from an incoming Kettle data stream when the total number of incoming rows is not known in advance. All rows have equal chance of being selected (uniform sampling)
    Splendid link. Thank you, Matt.

    Best regards
    Pradesh

  5. #5
    Join Date
    Nov 1999
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    9,729

    Default

    Written by Pentaho's Mark Hall of Weka fame.

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