1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Measures of Variability/Central Tendency For Certain Categories

  1. Mar 6, 2013 #1
    1. The problem statement, all variables and given/known data

    Suppose that I have the following groups/categories with how each is measured next to them:

    Response to light – measured on a scale of 1 to 4
    HDL levels – continuous value from 1 to 100
    Smoker status - smoker or non-smoker

    The question is as follows:

    What are the highest-level measures of central tendency and variability that can be used?



    2. Relevant equations

    If descriptive, equations would not apply.

    3. The attempt at a solution

    I know that central tendency includes mean, mode, and median and variability includes variance and standard deviation, but could someone please tell me what is meant by “highest-level measures”? Do I include the descriptive term (for example, central tendency answer "mean") or an actual measurement?

    Thank you.
     
  2. jcsd
  3. Mar 7, 2013 #2
    By “highest-level measures” I would assume that all the data is incorporated in the mean/variance estimate.

    Solutions:

    Answer 1: Use standard regression theory although the error terms (difference between fitted and observed) is not precisely normal (a mixture of dummy variables, categorical data and continuous). The Standard Error of Regression is the risk measure, the mean is given by the linear regression equation.

    Answer 2: Use the error terms from answer 1 as an input to a Box-Cox Analysis of transformation. Use the proposed transformation on the y-variable to correct (or approximately adjust) for normality issues.

    Answer 3: Use Least-Absolute deviations in place of a Least-Squares criteria. Apply risk measures (like average median deviation) and a median point estimate as discussed in the literature.
     
    Last edited: Mar 7, 2013
  4. Mar 8, 2013 #3

    statdad

    User Avatar
    Homework Helper

    I'm not sure why the previous poster gave what he/she did - not relevant.
    The question is essentially assessing your ability to determine the type of data that would be recorded. If the data is nominal (strictly categories) you wouldn't use mean or median for central tendency, nor would standard deviation qualify for variability. If the data is ordinal (can be arranged low to high) you could use median for central tendency. If the data were continuous (numerical) both mean and median would apply for central tendency, and standard deviation/variance for variability.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Measures of Variability/Central Tendency For Certain Categories
  1. Central Limit Theorem (Replies: 2)

Loading...