Describing Scores - Chapter 3 Describing and Presenting a...

Info icon This preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 3: Describing and Presenting a Distribution of Scores Outline: Measures of Variability Range, Variance, Standard Deviation Percentiles & Percentile Ranks Standard Scores z-Scores, T-scores Frequency Distribution Graphing Data
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Student Objectives: 1. Define and interpret range, variance and standard deviation. 2. Calculate range, variance and be able to find standard deviation with excel. 3. Define percentile and percentile rank and state how they can be used to interpret data. 4. Define standard scores and interpret their meanings. 5. Be able to calculate z and T Scores.
Image of page 2
Measures of Variability Spread or scatter of scores is referred Example: Group A: 80, 82, 83, 84, 86 Group B: 65, 75, 90, 90, 95 1. Range (R) Determined by subtracting the low score from the high score Formula: R = H x - L x Where: H x = high score, L x = low score Mean = Mean = Range = Range =
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2. Variance Spread of scores about How different the score is from Deviation score (d) = X X raw score mean Group 1 d d 2 Group 2 d d 2 X X - X (X X) 2 X X - X (X X) 2 7 2 4 9 4 16 6 1 1 7 2 4 5 0 0 5 0 0 4 -1 1 3 -2 4 3 -2 4 1 -4 16 ∑X 25 10 25 40 N 5 5 X 5 5 Range 4 8
Image of page 4
Variance (s 2 ) s 2 = ∑(X -X) 2 N - 1 Variance Group 1 = 10 ÷ 4 = 2.5 Variance Group 2 = 40 ÷ 4 = 10 Variance = square of the standard deviation
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
3. Standard Deviation ( std dev) Describes the Most commonly Used in other Homogeneous Data Heterogeneous Data s = standard deviation of a sample σ (Greek letter sigma) = standard deviation of a population
Image of page 6
s = ∑(X - X) 2 N - 1 Group 1: s = 10 = 2.5 = 1.58 4 Group 2: s = 40 = 10 = 3.16 4
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern