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Comparing plots
  • 时间:2024-11-03

Statistics - Comparing Plots


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Groups of population can be compared using box and whisker plots. Overall visible spread and difference between median is used to draw conclusion that there tends to be a difference between two groups or not.

Comparing plots

Formula

${P = frac{DBM}{OVS} imes 100 }$

Where −

    ${P}$ = percentage difference

    ${DBM}$ = Difference Between Medians.

    ${OVS}$ = Overall Visible Spread.

Rules

    For a sample size of 30 if this percentage is greater than 33% there tends to be a difference between two groups.

    For a sample size of 100 if this percentage is greater than 20% there tends to be a difference between two groups.

    For a sample size of 1000 if this percentage is greater than 10% there tends to be a difference between two groups.

Example

Problem Statement

Describe the difference between following sets of data.

Sr.No. Name Set A Set B
1 Max 12 15
2 UQ 10 13
3 Median 7 10
4 LQ 6 9
5 Min 5 6

Solution

Consider the following diagram −

Comparing plots

${OVS = 13 - 6 \[7pt] = 7 \[7pt] DBM = 10 -3 \[7pt] = 4 }$

Apply the formula

${P = frac{DBM}{OVS} imes 100 \[7pt] = frac{4}{7} imes 100 \[7pt] = 57.14 }$

As percentage is over 33% thus there is difference between Set A and Set B. It is pkely that Set B is greater than Set A.

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