Chapter 3

• The act of assigning numbers or symbols to characteristics of things according to rules.

  Measurement
• A set of numbers whose properties model empirical properties of the objects to which the numbers are assigned.

  Scale
• A scale used to measure a continuous variable.

  Continuous scale
• A scale use to measure a discrete variable.

  Discrete scale
• It refers to the collective influence of all the factors on a test score or measurement beyond those specifically measured by the test or measurement.


  Error
• It is the property of "moreness".

  Magnitude
• Properties of Scales:


  Magnitude

  Equal intervals

  Absolute zero
• Four Levels or Scales of Measurement:


  Nominal

  Ordinal

  Interval

  Ratio
• All scores are listed alongside the number of times each score occurred.

  Frequency Distribution
• Individual scores have been used and the data have not been grouped.

  Simple Frequency Distribution
• Test cores intervals, or class intervals , replace the actual test scores.


  Grouped Frequency Distribution
• It is a statistic that indicates the average or midmost score between the extreme scores in a distribution.

  Measures of Central Tendency
• It is the sum of the observed values in the distribution divided by the number of observations.

  Mean
• It is the middle score in the distribution. Determined by ordering the scores in a list by magnitude, either ascending or descending order.

  Median
• It refers to the most frequently occurring score.


  Mode
• It is the statistics that describes the amount of variation in a distribution.

  Measures of Variability
• It is the difference between the highest and the lowest score.

  High score- lowest score= r

  Range
• A distribution of test scores can be divided into 4 parts such that 25% of the test scores occur in each quarter.

  Quartile Deviation
• The dividing points between the four quarters in the distribution.

  Quartile
• It is a measure of variability equal to the difference between Q3 and Q1.


  Interquartile range
• It is equal to the interquartile range divided by 2


  Semi-interquartile range
• A measure of variability equal to the square root of the average squared deviations about the mean.


  Standard deviationSee an expert-written answer!We have an expert-written solution to this problem!
• It is equal to the arithmetic mean of the squares of the difference between the scores in a distribution and their mean.

  Variance
• The nature and extent to which a symmetry is absent.


  Skewness
• When relatively few of the scores fall at the high end of distribution.

  Positive Skew
• When relatively few of the scores fall at the lower end of distribution.


  Negative Skew
• Refers to the steepness of a distribution in its center

  Kurtosis
• Relatively flat


  Platykurtic
• Relatively peaked


  Leptokurtic
• Somewhere in the middle


  Mesokurtic
• A bell-shaped, smooth, mathematically defined curve that is highest at its center


  Normal curve
• It is the raw score that has been converted from one scale to another scale.

  Standard score
• Measures exactly how many standard deviations above or below the mean a data point is.

  Z-score
• A fifty plus or minus ten scale; a scale with a mean set at 50 and a SD set at 10.

  T scores
• A term that was a contraction of the words, standard and nine.

  Stanine
• Is a number that provides us with an index of the strength of the relationship between two things.

  Correlation coefficient
• It exists when two variables simultaneously decrease.


  Positive correlation
• This occurs when one variable increases while the other variable decreases.


  Negative correlation
• It is a correlation coefficient that measures linear correlation between two sets of data.

  Pearson r
• This coefficient correlation is frequently used when sample size is small and especially when both sets measurement are in ordinal form.


  Spearman rho