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29 Cards in this Set
- Front
- Back
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measurement |
the assignment of #s to represent the amt of an attribute present in an object/person, using specific rules |
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advantages to measurement |
removes guesswork, provides precise info, less vague than words (#s allow you to do statistical analyses & get answers) |
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Nominal measurement |
assigning #s to classify characteristics into categories; interchangeable lowest level of evidence b/c it only uses #s to categorize so they have no meaning |
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Ordinal Measurement |
ranking objects based on their relative standing on an attribute; you can't make inferences; quantitative ordering of values e.g., educational level |
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interval measurement |
objects ordered on a scale that has equal distances b/n points on the scale; # has meaning e.g., depression scale, likert scale |
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Ratio measurement |
equal distances b/n score units; there is a rational, meaningful zero; highest level of evidence; gives you actual #s e.g., BP, wt, age, etc. |
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obtained score |
an actual data value for a participant e.g., anxiety scale score obtained score = true score +/- error |
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True score |
the score that would be obtained with an infallible measure |
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Error |
the error of measurement, caused by factors that distort the measurement |
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4 factors contributing to errors of measurement |
1. situational contaminants (temp/smell of environment that affects how honestly & purposefully subjects answer) 2. transitory personal factors (e.g., fatigue) 3. response set biases (social desirability, nay-sayers, extreme responses 4. item sampling (what was used to measure the variable?) |
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reliability |
the consistency & accuracy w/which an instrument measures the target attribute; being able to use the same instrument multiple times and getting the same answer |
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reliability coefficient |
used to compute reliability assessments; done by a computer -range from .00-1.00 (1 is perfect score; never seen) <.70 considered unsatisfactory .80+ are desirable |
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What 3 aspects of reliability do we evaluate? |
stability, internal consistency, equivalence |
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stability |
the extent to which scores are similar on 2 separate administrations of an instrument -evaluated by test-retest reliability -requires participant to complete the same instrument on 2 occasions -appropriate for relatively enduring attributes (e.g., creativity) |
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Internal consistency |
the extent to which all the items on an instrument are measuring the same attribute -evaluated by administering instrument on one occasion -appropriate for most multi-item instruments *most widely used approach to assess reliability -assessed by computing coefficient alpha (Cronbach's alpha) Alphas >/= .80 highly desirable |
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Equivalence |
the degree of similarity b/n alternative forms of an instrument or b/n multiple raters/observers using an instrument -most relevant for structured observations -assessed by comparing agreement b/n observations or ratings of 2+ observers (interobserver/interrater reliability) |
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Reliability Principles |
-low reliability can undermine adequate testing -of hypotheses -reliability estimates vary depending on procedure used to obtain them -lower in homogeneous vs. heterogeneous samples -lower in shorter vs. longer multi-item scales |
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Validity |
the degree to which an instrument measures what it's supposed to measure -aspects: face validity, content validity, criterion-related validity, construct validity |
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face validity |
refers to whether the instrument looks as though it is an appropriate measure of the construct -based on judgment; no objective criteria for assessment |
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content validity |
the degree to which an instrument has an adequate sample of items for the construct being measured -evaluated by expert evaluation, often via a quantitative measure- the content validity index (CVI) 0.9+ is desirable |
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criterion-related validity |
the degree to which the instrument is related to an external criterion -validity coefficient: calculated by analyzing the relationship b/n scores on the instrument and the criterion -predictive and concurrent validity |
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predictive validity |
the instrument's ability to distinguish ppl whose performance differs on a future criterion (e.g,. Kaplan test predicting NCLEX scores) |
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concurrent validity |
the instrument's ability to distinguish individuals who differ on a present criterion; substituting one measure for another (e.g., AP class exams earning college credit) -one score replaces another |
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construct validity |
degree to which the measure you're using is addressing the theoretical construct you want to measure -what is the instrument really measuring? -Does it adequately measure the construct of interest? -Convergent & discriminant validity (are they converging in what they measure of are they 2 discriminant things?) |
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methods of assessing construct validity |
known-groups technique, testing relationships based on theoretical predictions, factor analysis |
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known-groups technique |
2 or more groups that know they should be diff when given the same instrument; test is invalid is the answer is the same |
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factor analysis |
complex process done by computer analysis; testing an attribute to place like terms into subgroups |
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sensitivity |
the instrument's ability to correctly identify a "case" (e.g., diagnose a condition) -e.g., how sensitive is this test at diagnosing strep throat? Am I getting a true positive? |
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Specificity |
the instrument's ability to correctly identify non-cases, to screen out those w/o the condition e.g., tests the true negative |
