Math Problem Statement

The English statistician Karl Pearson​ (1857-1936) introduced a formula for the skewness of a distribution.

                                               Upper P equals StartFraction 3 left parenthesis x overbar minus median right parenthesis Over s EndFractionP=3x−medians

Most distributions have an index of skewness between

minus−3

and 3. When P​ > 0 the data are skewed right. When P​ < 0 the data are skewed left. When P​ = 0 the data are symmetric. Calculate the coefficient of skewness for each distribution. Describe the shape of each.

Question content area bottom

Part 1

​(a)**** The coefficient of skewness for

x overbarx

​=

1717​,

s​ =

2.32.3​,

median​ =

1818

is P​ =

enter your response here.

​(Round to the nearest hundredth as​ needed.)

Solution

To calculate the coefficient of skewness PP, we use the formula introduced by Karl Pearson:

P=3(xˉmedian)sP = \frac{3(\bar{x} - \text{median})}{s}

Given dataTo calculate the coefficient of skewness PP, we use the formula introduced by Karl Pearson:

P=3(xˉmedian)sP = \frac{3(\bar{x} - \text{median})}{s}

Given

  • Mean xˉ=17\bar{x} = 17
  • Standard deviation s=2.3s = 2.3
  • Median median=18\text{median} = 18

Step-by-step calculation:

  1. Subtract the median from the mean: xˉmedian=1718=1\bar{x} - \text{median} = 17 - 18 = -1

  2. Multiply the result by 3: 3(xˉmedian)=3(1)=33(\bar{x} - \text{median}) = 3(-1) = -3

  3. Divide the result by the standard deviation ss: P=32.31.30P = \frac{-3}{2.3} \approx -1.30

Conclusion:

The coefficient of skewness is approximately P=1.30P = -1.30.

Since P<0P < 0, this indicates that the data are skewed left.


Would you like further clarification on this, or any details on the steps?

Here are 5 follow-up questions to expand on this:

  1. What does a skewness value of 0 signify in a data distribution?
  2. How does skewness affect the interpretation of a dataset's mean and median?
  3. Can skewness alone determine the normality of a dataset? Why or why not?
  4. What are some real-life examples of left-skewed distributions?
  5. How would increasing the standard deviation ss affect the skewness value?

Tip: Skewness helps assess the symmetry of a dataset. A strong positive or negative skew indicates more extreme values on one side of the distribution.

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Math Problem Analysis

Mathematical Concepts

Statistics
Skewness
Descriptive Statistics

Formulas

Skewness formula: P = (3(x̄ - median)) / s

Theorems

Karl Pearson's skewness formula

Suitable Grade Level

Grades 10-12