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• Descriptive statistics


  Methods used to provide a concise description of a collection of quantitative information
• Inferential statistics


  Methods used to make inferences from observations of a small group of people known as a sample to a larger group of individuals known as population
• Measurement


  An act of assigning numbers or symbols to characteristics according to rules
• Scale

  A set of numbers which are used in a particular system of measuring or comparing things
• Continuous scale


  • Measures a continuous variable; quantifiable; can be divided
• Discrete scale


  • Countable data
• Error


  The degree to which data is inaccurate
• Properties of Scale


  • Magnitude
  • Intervals
  • Absolute zero
• Magnitude


  The property of moreness and comparison
• Magnitude


  • I am better than myself last year. I am the first honor.
• Intervals


  The difference between two variables at any place on the scale has the same meaning as the difference between two other points that differ by the same number of scale units
• Intervals


  • 5, 10, 15, 20
• Absolute zero


  Nothing of the property being measured exists
• Absolute zero


  • Nothing, zero, absence
• Scales of Measurement


  • Nominal
  • Ordinal
  • Interval
  • Ratio
• Nominal scales


  Involve classification or categorization
• Nominal scales


  • Gender, name, course, year level
• Ordinal scales


  Permit classification and rank ordering
• Ordinal scales


  • Grades, competition result, honors
• Interval scales


  Contain equal intervals between numbers
• Interval scales


  • Time, temperature, years
• Ratio scales


  Has a true zero point
• Ratio scales


  • Height, weight, age, money
• NOIR and MIA


  • NOMINAL - no MIA
  • ORDINAL - has M
  • INTERVAL - has MIA
  • RATIO - has MIA
• Distribution


  A set of test scores arrayed for recording or study
• Raw score


  A straightforward, unmodified accounting of performance that is usually numerical
• Frequency Distribution


  All scores are listed alongside the number of times each score occurred
• Frequency Distribution


  • Suppose there are 40 students in a class and were asked what their favorite subject is.
• Grouped Frequency Distribution


  Test score intervals or class intervals replace the actual test scores
• Grouped Frequency Distribution


  • The class with 25 students took a 20-item test and their scores were shown through a grouped frequency distribution.
• Graphs used to illustrate frequency distributions

  • Histogram
  • Bar graph
  • Frequency polygon
• Histogram


  A graph with vertical lines drawn at the true limits of each test score (or class interval), forming a series of contiguous rectangles
• Bar graph


  Numbers indicative of frequency appear on the Y-axis, and reference to some categorization appears on the X-axis
• Frequency polygon


  Data illustrated by a continuous line connecting the points where test scores or class intervals (as indicated on the X-axis) meet frequencies (as indicated on the Y-axis)
• Measure of central tendency


  A statistic that indicates the average or midmost score between the extreme scores in a distribution
• Mean


  The arithmetic mean (or, more simply, mean), which is referred to in everyday language as the "average". It takes into account the actual numerical value of every score.
• Mean


  • 2 5 3 1 6 3 10 10 = 5
• Median


  The middle score in a distribution, determined by arranging the scores from ascending or descending order
• Median


  • 2 5 3 1 6 3 10 10 = 1 2 3 3 5 6 10 10 = 4
• Mode


  The most frequently occurring score in a distribution of scores