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Questions and Answers
What is the primary feature of nominal scales?
What is the primary feature of nominal scales?
What is a key difference between ordinal and nominal scales?
What is a key difference between ordinal and nominal scales?
What is a characteristic of interval scales?
What is a characteristic of interval scales?
What is not a feature of interval scales?
What is not a feature of interval scales?
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What can be inferred about the difference in intellectual ability represented by IQs of 80 and 100?
What can be inferred about the difference in intellectual ability represented by IQs of 80 and 100?
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What is a presumption inherent in the use of interval scales?
What is a presumption inherent in the use of interval scales?
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What is Alfred Binet's view on the data derived from an intelligence test?
What is Alfred Binet's view on the data derived from an intelligence test?
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What is the primary purpose of an intelligence test, according to Alfred Binet?
What is the primary purpose of an intelligence test, according to Alfred Binet?
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What is the variance equal to?
What is the variance equal to?
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What does a positively skewed distribution indicate about a test?
What does a positively skewed distribution indicate about a test?
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What is kurtosis?
What is kurtosis?
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Who is credited with first referring to the curve as the normal curve?
Who is credited with first referring to the curve as the normal curve?
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What does a negatively skewed distribution indicate about a test?
What does a negatively skewed distribution indicate about a test?
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What is the formula for the standard deviation based on?
What is the formula for the standard deviation based on?
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What does the term 'age norm' refer to in scholarly literature?
What does the term 'age norm' refer to in scholarly literature?
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What is the term used to describe the nature and extent to which symmetry is absent in a distribution?
What is the term used to describe the nature and extent to which symmetry is absent in a distribution?
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Who made substantial contributions to the development of the normal curve in the early nineteenth century?
Who made substantial contributions to the development of the normal curve in the early nineteenth century?
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What is the purpose of administering a test to a representative sample of test takers?
What is the purpose of administering a test to a representative sample of test takers?
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What is a normative sample?
What is a normative sample?
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What is race norming?
What is race norming?
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Why do some test manuals provide user norms or program norms?
Why do some test manuals provide user norms or program norms?
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What is test standardization?
What is test standardization?
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In the process of developing a test, what does a test developer target?
In the process of developing a test, what does a test developer target?
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What is the plural form of 'norm'?
What is the plural form of 'norm'?
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What is the influence of culture observed in the context of testing and assessment?
What is the influence of culture observed in the context of testing and assessment?
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What is criterion-related validity a judgment of?
What is criterion-related validity a judgment of?
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What is concurrent validity an index of?
What is concurrent validity an index of?
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What is a characteristic of an adequate criterion?
What is a characteristic of an adequate criterion?
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What is criterion contamination?
What is criterion contamination?
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What type of validity is concerned with the degree to which a test score predicts some criterion measure?
What type of validity is concerned with the degree to which a test score predicts some criterion measure?
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What is an example of a criterion measure that is contaminated?
What is an example of a criterion measure that is contaminated?
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What is the purpose of establishing the validity of a criterion measure?
What is the purpose of establishing the validity of a criterion measure?
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What is the term referred to when a portion of the universe of people is deemed to be representative of the whole population?
What is the term referred to when a portion of the universe of people is deemed to be representative of the whole population?
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What type of sampling occurs when every member of the population has the same chance of being included in the sample?
What type of sampling occurs when every member of the population has the same chance of being included in the sample?
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What is the term for the score at or below which a certain percentage of scores in a distribution fall?
What is the term for the score at or below which a certain percentage of scores in a distribution fall?
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What is the purpose of administering a test to a sample of the population?
What is the purpose of administering a test to a sample of the population?
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What type of sample is selected because it is convenient or available for use?
What type of sample is selected because it is convenient or available for use?
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What is the term for the process of selecting a portion of the universe deemed to be representative of the whole population?
What is the term for the process of selecting a portion of the universe deemed to be representative of the whole population?
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What is the term for the distribution of scores obtained from a sample of test takers?
What is the term for the distribution of scores obtained from a sample of test takers?
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What is the term for the people in the normative sample when they are the same people on whom the test was standardized?
What is the term for the people in the normative sample when they are the same people on whom the test was standardized?
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Study Notes
Scales of Measurement
- Nominal scales: simplest form of measurement, involve classification or categorization based on one or more distinguishing characteristics, mutually exclusive and exhaustive categories.
- Ordinal scales: permit classification and rank ordering on some characteristic, data is ordinal in nature, no absolute zero point.
- Interval scales: contain equal intervals between numbers, each unit on the scale is exactly equal to any other unit, no absolute zero point.
Descriptive Statistics
- Variance: equal to the arithmetic mean of the squares of the differences between the scores in a distribution and their mean.
- Formula for variance (s2): deviation scores.
- Standard deviation: square root of the variance.
- Skewness: nature and extent to which symmetry is absent in a distribution.
- Positive skew: relatively few scores fall at the high end of the distribution, may indicate the test was too difficult.
- Negative skew: relatively few scores fall at the low end of the distribution, may indicate the test was too easy.
- Kurtosis: steepness of a distribution in its center, platykurtic (relatively flat), leptokurtic (relatively peaked), or mesokurtic.
The Normal Curve
- Development of the concept of a normal curve began in the 18th century with Abraham Demurer and the Marquis de Laplace.
- Karl Friedrich Gauss made substantial contributions, referred to as the “Laplace-Gaussian curve”.
- Karl Pearson coined the term “normal curve”, used to refer to behavior that is usual, average, normal, standard, expected, or typical.
Norms
- Norms: test performance data of a particular group of test takers, designed for use as a reference when evaluating or interpreting individual test scores.
- Normative sample: group of people whose performance on a particular test is analyzed for reference.
- Norming: process of deriving norms, can be modified to describe a particular type of norm derivation, e.g. race norming.
- User norms or program norms: descriptive statistics based on a group of test takers in a given period of time, rather than norms obtained by formal sampling methods.
Sampling to Develop Norms
- Standardization or test standardization: process of administering a test to a representative sample of test takers to establish norms.
- Population: complete universe or set of individuals with at least one common, observable characteristic.
- Sampling: process of selecting a portion of the universe deemed to be representative of the whole population.
- Stratified sampling: process of selecting a sample to prevent sampling bias.
- Purposive sample: sample selected because it is believed to be representative of the population.
- Incidental sample or convenience sample: sample that is convenient or available for use, generalization of findings must be made with caution.
Types of Norms
- Percentiles: dividing a distribution of scores into 100 equal parts.
- Xth percentile is equal to the score at or below which x% of scores fall.
Validity
- Criterion-related validity: judgment of how adequately a test score can be used to infer an individual’s most probable standing on some measure of interest.
- Concurrent validity: degree to which a test score is related to some criterion measure obtained at the same time.
- Predictive validity: degree to which a test score predicts some criterion measure.
- Criterion: standard against which a test or a test score is evaluated.
- Characteristics of a criterion:
- Relevance: pertinent or applicable to the matter at hand.
- Validity: evidence exists that the criterion is valid for the purpose for which it is being used.
- Lack of contamination: criterion measure is not based on predictor measures.
- Characteristics of a criterion:
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Description
This quiz covers the basics of nominal and ordinal scales in statistics, including classification, categorization, and rank ordering.
