STA104 WEEK 6
14 - 20 NOVEMBER 2022
Kuliah 1: 30 Mac - 24 May 2026
14 - 20 NOVEMBER 2022
CHAPTER 2: DESCRIBING & GRAPHING DATA
Topics:
Coefficient of Variation (CV)
Measures of Skewness
Drawing Box Plot
First Class:
LEARNING OBJECTIVE 1
Coefficient of Variation (CV)
Students need to know how to calculate and made correct decision using coefficient of variation (CV).
ππΌ Refer Pg. 59
ππΌ Watch Video V1W6
ππΌ Do Exercise 2(a) Pg. 60
Answer:Β
CV (A) = 14.12%
CV (B) = 12.31%
CV (C) = 15.38%
So, class B has the most consistent performance since its coefficient of variation is the lowest.
Video V1W6: Coefficient of Variation (CV)Β
LEARNING OBJECTIVE 2
Measures of Skewness
Students need to know how to calculate and made correct decision using measure of skewness.
ππΌ Refer Pg. 48 - 49
ππΌ Watch Video V2W6
Correction in my YouTube video (V2W6):
Note that, at minute 18:56 until end of the video, there is an accidental mistake where I interpreted the meaning of skewed to the left is "There are more younger tourist as compared to the average age OR There are less older tourist as compared to the average." It is supposed to be the otherwise.
ππΌ Watch Video V3W6 (extra explanation)
ππΌ Redo Example (c) Pg. 55
ππΌ Do Exercise 1(c) Pg. 58
Answer:Β
By using formula Pearson coefficient of skewness with info mean and mode:
Skewness = 0.56 (skewed to the right)
It indicates that there are more lower weekly sales as compared to the average weekly sales.
Note: You can use formula with mean and median too since in this example you have mean, median and mode values.
ππΌ Do Exercise 2(b) Pg. 60
Answer:Β
By using formula Pearson coefficient of skewness with info mean and mode:
Class A:Β Skewness = 1.67
Class B:Β Skewness = 0
Class C:Β Skewness = -2Β Β
So, Class A has a distribution skewed to the right.
ππΌ Redo Example 24 (No.5) Pg. 65 - 66
Extra Note:
There are 2 ways to detect skewness or shape of data distribution for a set of data.
1) Graphical Method
ππΌ By using stem and leaf plot, histogram and box plot
2) Numerical Method
ππΌ By calculating Pearson coefficient of skewness
ππΌ By comparing values of mean, median and mode
Video V2W6: Measures of SkewnessΒ
Video V3W6: SkewnessΒ
Second Class
LEARNING OBJECTIVE 3
Drawing Box Plot
Students need to know how to draw box-and-whisker plot.
ππΌ Refer Pg. 69 (ignore outlier)
ππΌ Watch Video V4W6Β
ππΌ Do Example 25 Pg. 70
ππΌ Try draw box plot using data on Pg. 54 and Pg. 57
πTo ease you in drawing the box plot with proper scale, please use graph paper.
Video V4W6: Drawing Box PlotΒ