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Exam 2 Chapter Four Choosing Variables and Measurements Conceptual variable an abstract idea that forms the basis of a research hypothesis o Ex Study time job satisfaction temperature o Circles in diagram Measured variable numbers that represent the conceptual variables o Ex Seconds of study Likert scale monthly sales degrees farenheit o Squares in diagram Operational definition a precise statement of how a conceptual variable is turned into a measured variable o Ex Conceptual employee satisfaction Operational of days per month that employee shows up for work The lines from squares to circles are the operational definitions If the conceptual variables correlate and if the operational was correct a correlation between measured variables will be seen too o Converging operations when there is more then one way to operationalize a conceptual variable depending on what is the focus of the research Helps triangulate the conceptual variable to get a fuller measure of it Scales of Measurement Measurement is a procedure for classifying data the set of categories used for classification is called the scale of measurement Nominal Scale categories have different names but order does not matter o Reflects qualitative differences Sex ethnicity Can be assigned numbers Male 1 female 2 Statistical procedure non parametric Frequency counts mode chi square frequency differences We can say that two people differ but you cant find an average of the differences Ordinal Scale categories have different names AND are organized sequentially o Ex Horse race o We can determine If there are differences The direction of the differences and or rank of order o We CANNOT say how big those differences are doesn t measure intervals o Appropriate statistics non parametric Median mode rank sum correlation Wilcoxon rank sum test non parametric ANOVA Ex Taste test between 3 sodas Can tell how much more one is liked over the other but not by how much Interval Scale categories are organized sequentially and all categories are the same size o Has an arbitrary zero point not a true zero Temperature in Celsius o Can determine how large or small differences are o Statistical procedures parametric Mean median mode standard deviation correlation t test anova o Consists of equal ordered categories anchored by a non arbitrary zero point The Ratio Scale true zero Ex Weight percent correct reaction time to a stimulus Zero is the variable being measured and can help find multiples Appropriate Statistics Parametric Mean median mode standard deviation correlation ratios t tests ANOVA Summary of Scales Nominal Ordinal o Can say only if a difference exists sex religion o Can tell us the direction of the difference soda test horse race Interval Ratio o Can tell us the direction and size Celsius o As above and ratio of the difference true zero KELVIN Factors Affecting Your Choice of a Scale of Measurement Information Yielded o Nominal scale yields the least information o Ordinal scale adds some crude information o Interval and ratio scales yield the most information Statistical Tests Available o The statistical tests available for nominal and ordinal data non parametric are less powerful than those available for interval and ratio data parametric Ecological Validity o Sometimes your research requires you to use a measure that reflects what people do in the real world a nominal guilty not guilty verdict o Such scales have ecological validity o When necessary choose an ecologically valid measure even if it means loss of info o These are things you can do to gain needed information Include an additional scale interval Create a composite scale by combining a nominal and interval scale Incorporate features of ecologically valid scale into a more informative scale Adequacy of a Dependent Measure Adequacy of a dependent measure is related to the sensitivity of the measure and range effects Sensitivity o Is a dependent measure sensitive enough to detect behavior change Marital happiness Divorce or of arguments per month o An insensitive measure will not detect subtle behaviors Range Effects o We often run into range effects when our tests are too easy or too hard o Occur when a dependent measure has an upper or lower limit Ceiling effect when a dependent measure has an upper limit Floor effect when a dependent measure has a lower limit o Affect data in two ways Limiting values of your highest or lowest data point Variability of scores within affected treatments is reduced May cause misleading results from statistical analysis of data Types of Dependent Variables Behavioral Measure o Record actual behavior of subjects o Several types Frequency count of the number of behaviors that occur Latency the amount of time it takes for a behavior to occur Number of Errors the number of incorrect responses made o May not allow you to determine the underlying cause for behavior Physiological Measure o Physical measure of body function o Typically requires special equipment o Most physiological measures are non invasive Some require an invasive procedure o Allow you to make precise measurements of arousal of a subject s body o Must infer psychological states Implicit Measures o Implicit Associations Test IAT is a popular example of an impact measure of racial bias Explained themselves as self or other and panic or calm o Disguise the goal of the test Free Format Self Report o Allow them to respond with no constraints o Projective Measures Thematic Apperception Test TAT Free response to picture of people that show emotions indirectly in the images instead of within themselves Rorschach Ink Blot Test Free response to images o Associative Lists Study stereotyping o Think Aloud Protocol o Coding Issues Empirical Support is critical Listed races and people wrote descriptive words Say out loud thought they have while completing a task Hard to analyze data and give it measured variables because it reduces freedom Content analysis process of coding free response data Self Report Measures o Participants report on their own behavior or state of mind o Self measures are popular and easy to use but may have questionable You cannot be sure that a participant is telling the truth reliability and validity o Fixed Format Self Report Likert scale 1 7 Indicate agreement or disagreement Rosenberg scale Semantic Differential Topic is presented at the top of the page Items consist of pairs of adjectives located at the endpoints of a standard response format Whether they feel

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