PDU 207 Basic Statistics: Central Tendency

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Central tendency as a part of descriptive statistic
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PDU 207 Basic Statistics: Central Tendency

  1. 1. PDU 207 STATISTIK DASAR SEKSI E SEMESTER GASAL 2016/2017 FAKULTAS PSIKOLOGI / PROGRAM STUDI S1 PSIKOLOGI Central Tendency KULIAH IV – 29 AGUSTUS 2016
  2. 2. Menguasai teknik-teknik statistika deskriptif dan statistika inferensial,
 secara khusus terkait dengan: • Tujuan dilakukannya perhitungan central tendency; • Definisi dan perhitungan tiap teknik pengukuran central tendency. Memiliki kemampuan menyampaikan argumentasi dan penalaran
 dengan bahasa yang tepat, khususnya berkaitan dengan: • Pemilihan teknik perhitungan central tendency yang paling tepat sesuai jenis data
 dan tujuan pengukuran. One-Day Objectives
  3. 3. Introduction to
 Central Tendency
  4. 4. PDU 207 STATISTIK DASAR 2016 © Ardhiati 4 • Independent Variable: Instructor • Dependent Variable: Short-Term Memory Capacity 5 4 3 3 4 4 7 5 2 5 4 3 4 8 3 5 5 6 6 4 8 6 6 5 7 8 8 7 8 9 7 8 7 9 5 8 7 7 6 7 GROUP 1 GROUP 2 IMAGE SOURCES: unitedgiveaways.com/tag/scarlett-johansson/ ;
 fansshare.com/gallery/photos/12369098/julia-bperez-bcopy/
  5. 5. PDU 207 STATISTIK DASAR 2016 © Ardhiati 5 • Independent Variable: Instructor • Dependent Variable: Short-Term Memory Capacity GROUP 1 GROUP 2 IMAGE SOURCES: unitedgiveaways.com/tag/scarlett-johansson/ ;
 fansshare.com/gallery/photos/12369098/julia-bperez-bcopy/ 0 1 3 4 6 7 9 10 1 2 3 4 5 6 7 8 9 10 Group 1 Group 2 How far these
 two groups differ? CENTRAL
 TENDENCY
  6. 6. PDU 207 STATISTIK DASAR 2016 © Ardhiati 6 The general purpose of
 descriptive statistical methods
 is to summarize, organize, and simplify data; Organize or summarize them
 in a form that is more manageable. (Gravetter & Wallnau, 2012: 72) CENTRAL
 TENDENCY
  7. 7. PDU 207 STATISTIK DASAR 2016 © Ardhiati Central Tendency 7 Central tendency is a statistical measure
 to determine a single score that defines
 the center of a distribution. The goal of central tendency is to find
 the single score that is most typical or
 most representative of the entire group. THE DEFINITION (Gravetter & Wallnau, 2012: 73)
  8. 8. PDU 207 STATISTIK DASAR 2016 © Ardhiati 8 CENTRAL
 TENDENCY THE
 MEAN THE
 MEDIAN THE
 MODE
  9. 9. The Mean,
 Median, & Mode
  10. 10. PDU 207 STATISTIK DASAR 2016 © Ardhiati The Mean 10 • the sum of the scores divided by the number of scores; • the amount each individual receives when the total (∑X) is
 divided equally among all of the individuals (N) in the distribution; • a balance point for the distribution. FOR A DISTRIBUTION IS… (Gravetter & Wallnau, 2012: 74-77)
  11. 11. PDU 207 STATISTIK DASAR 2016 © Ardhiati The Mean 11 • Changing a score Changing the value of any score changes the mean; • Introducing a new score or
 removing a score Adding a new score to a distribution, or removing
 an existing score, usually changes the mean; ALTERNATIVE DEFINITION (Gravetter & Wallnau, 2012: 79-82) • Adding or subtracting a constant
 from each score If a constant value is added to every score in a distribution, the same constant is added to the mean; • Multiplying or dividing each score
 by a constant If every score in a distribution is multiplied by
 (or divided by) a constant value, the mean changes
 in the same way.
  12. 12. PDU 207 STATISTIK DASAR 2016 © Ardhiati The Median 12 • the midpoint of the list if the scores in a distribution are listed in order
 from smallest to largest; • the point on the measurement scale below which 50% of the scores in the distribution are located. FOR A DISTRIBUTION IS… (Gravetter & Wallnau, 2012: 83-85)
  13. 13. PDU 207 STATISTIK DASAR 2016 © Ardhiati The Mode 13 • the score or category that has the greatest frequency. FOR A DISTRIBUTION IS… (Gravetter & Wallnau, 2012: 87-89)
  14. 14. PDU 207 STATISTIK DASAR 2016 © Ardhiati 14 Locate
 the “center”
 of the distribution! 1 2 3 4 5 6 7 8 9 f X 1 2 3 4 5 6 7 8 9 f X1 2 3 4 5 6 7 8 9 f X (Gravetter & Wallnau, 2012: 74)
  15. 15. PDU 207 STATISTIK DASAR 2016 © Ardhiati 15 There are other things need to be considered
 before analyzing the central tendency
 of the data. Not all techniques
 are appropriate for all kind of data. SO…
  16. 16. PDU 207 STATISTIK DASAR 2016 © Ardhiati Selecting a Measure 16 OF CENTRAL TENDENCY The Mean The Median The Mode Ratio/Interval Scale Undetermined Values Ordinal Scale Nominal Scale Discrete Variables Describing Shape Open-Ended Distribution ✓ Extreme Scores/Skewed Distributions ✓ ✓ ✓ ✓ ✓ ✓ ✓ (Gravetter & Wallnau, 2012: 89-92)
  17. 17. Central Tendency &
 The Shape of Distribution
  18. 18. PDU 207 STATISTIK DASAR 2016 © Ardhiati Central Tendency 18 IN A SYMMETRICAL DISTRIBUTION The mean and median are close together
 in the center of the distribution. & THE SHAPE OF DISTRIBUTION (Gravetter & Wallnau, 2012: 95-96)
  19. 19. PDU 207 STATISTIK DASAR 2016 © Ardhiati Central Tendency 19 IN A SKEWED DISTRIBUTION & THE SHAPE OF DISTRIBUTION (Gravetter & Wallnau, 2012: 95-96)
  20. 20. PDU 207 STATISTIK DASAR 2016 © Ardhiati 20 WANT TO KNOW MORE? Gravetter, F.J. & Wallnau, L.B. (2012).
 Statistics for the behavioral sciences (9th ed.).
 Australia: WADSWORTH CENGAGE Learning.

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