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Interpeting data figures - its rather simple but not soo simple

  1. Jan 20, 2008 #1
    Can Someone please tell me how I can interpret the skewness of a distribution using quartiles.

    I know that if Q2 – Q1 > Q3 – Q2 : Negative skew and if Q3 – Q2 > Q2 – Q1: Positive Skew and if Q2 –Q1 = Q3 – Q1: Symmetrical data dispersion

    What I really need to know is how to use the above to interpret data sets and be able to apply it to all situations. I’ve never really been able to say more than the above in GCSE and A-level and this got me an A in math at both stages but at Uni I really need to interpret this stuff.

    Can I say that if the data is negatively skewed then the data values tend to be generally very small? What confuses me is that we will always have 25% of the data lying below Q1 and 50% of the data lying either side of the median and 75% below Q3. But how can we use this to give analysis??

  2. jcsd
  3. Jan 20, 2008 #2


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    Homework Helper

    That is correct; but the data values of Q1 and Q3 will differ from one sample to the other.
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