SOCIAL STATISTICS

TABLE OF CONTENTS

2. Level of Measurement / Data Level
3. Introduction to the Two Measures in Statistics
4. Median as a Measure of Location
5. The Quartiles
6. The Quartiles and Median of Grouped Data
7. The Mode
8. More on Calculating The Variance
9. Anatomy of Frequency Distribution Tables
10. Calculating the Mean of Grouped Data
11. Calculating the Sample Variance of Grouped Data (without calculating the mean)
12. Constructing The Frequency Distribution Table
13. The Theoretical Probabilities
14. Mutually Exclusive Events
15. Independent Events
16. Random Variables and Probability Distributions
17. Binomial Distribution
18. Introduction to Hypothesis Testing
19. Testing for Population Means
20. Spearman's Rank Correlation Coefficient
21. Simple Linear Regression

References:
Kreyszig, E. (1993). Advanced Engineering Mathematics, John Wiley&Sons, Inc.
Lind (2012). Statistical Techniques in Business and Economics, McGraw-Hill Irwin
Siegel (1988), Nonparametric Statistics for the Behavioral Sciences, McGraw-Hill, Inc.
Spiegel, M. R. (1981). Theory and Problems of Statistics, McGraw-Hill International Book Company
Walpole, R. E. (1993). Probability&Statistics for Engineers and Scientists, Macmillan Publishing Co.

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CONSTRUCTING THE FREQUENCY DISTRIBUTION TABLE

The frequency distribution table is a table that divides data into groups (classes) and shows how many data values occur in each group/class. Below is an example of frequency distribution table. Now we are learning how to create a frequency distribution table. Suppose we have a collection of ungrouped data on last year’s advertising expenditures of 40 logistics companies, recorded in millions Rupiahs. To construct a frequency distribution table of the ungrouped data, apply the following steps. Step 1: Find the range of the data The range (R) is defined as the difference between the largest data and the smallest data. In this case, R = 307 - 242 = 65. Step 2: Determine the number of categories/classes (k) Applying Sturges rule (k = 1 + 3,322 log n, where n = the number of data), we have: $k = 1 + 3.322 \: log \: 40 \approx 6.32$ As the value of k must be a natural number, 6.32 is rounded up to 7, so k = 7. Step 3: Determine the class width (c) To find c, use $...

THE QUARTILES AND MEDIAN OF GROUPED DATA

In this post, we will learn how to determine the quartiles when some quantitative data are presented in a frequency distribution table. For example, we have the following data, showing Flesch Readability Score of 80 monthly bulletin articles published by Britt and Co. Ltd. Find the quartiles of these readability scores. To answer this, first augment the table with a new column to the right of the frequency column, namely Data Numbers column. There are 5 data in the first class, so the class contains data no. 1 to no. 5. There are 7 data in the second class, so the class contains data no. 6 to no. 12. There are 13 data in the third class, so the class contains data no. 13 to no. 25. Continuing this way, we get the following: In this case, finding the first quartile means finding the 20 th data, after the data have been ordered from the smallest to the highest (20 = ¼ x 80). Note that the 20 th data is in the third class (20 is ...

CALCULATING THE MEAN OF GROUPED DATA

Sometimes quantitative data are presented in the form of a frequency distribution table (FDT). A typical FDT is as follows. Suppose that the table above presents the duration of 16 cell phone conversations between pairs of teens. There are 2 conversations with duration from 30 seconds to 44 seconds, 3 conversations with duration from 45 seconds to 59 seconds, etc. How do we calculate the mean of the data? Step 1: Determine the midpoint of each class If M i denotes the midpoint of class i, $M_{i} = \frac{LB_{i}+UB_{i}}{2}$ where LB i = lower bound of class i and UB i = upper bound of class i. The lower bounds of class 1, 2, 3, 4, 5 are 30, 45, 60, 75, 90, respectively and the upper bounds are 44, 59, 74, 89, 104, respectively. Then, $M_{1} = \frac{30+44}{2} = 37$. Similarly, $M_{2} = \frac{45+59}{2} = 52$. Continuing this way, we have the following table. Step 2: Multiply each class frequency f i by the corresponding class midpoint ...

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