Presentation on theme: "CRIM 430 Lecture 7 Creating Measures for Data Collection."— Presentation transcript:
CRIM 430 Lecture 7 Creating Measures for Data Collection
The Basis of Creating Measures Conceptual definition: Result of conceptualization—a working definition specifically assigned to a term Operational definition: Definition that clarifies exactly how the concept will be measured—most be specific and unambiguous Use the operational definition to conduct measurements in the real world These are decisions that you must make based on the literature and your expertise Creating measures or variables=Process of assigning numbers or labels to units of analysis in order to represent conceptual properties Once your variables are defined, use them to capture observations. Those observations, in turn, are scored to allow for analysis
Levels of Measurement Nominal Measures Variables only used to capture exhaustiveness and exclusiveness (no order to responses) Examples: Gender, race, city of residence Ordinal Measures Each attribute represents more or less of the variable Examples: Sentence type, crime seriousness, fear of crime, opinion of police Interval Measures Rank ordered attributes and the distance between attributes has meaning and is measurable Examples: Temperature, age, years sentenced to prison Ratio Measures Rank ordered attributes; distance is measurable; attributes are based on a zero starting point Example: Amount of fine imposed
Single Item Measures Single items involve one question to capture the data you need Single items are best used to capture demographic information, such as gender, or information that is straightforward in nature Single items are limited in their ability to represent more complex concepts—for example, single items are not appropriate to capture an attitude toward “x”
Composite Measures Single measures do not necessarily have high reliability and validity when the concept is more complex in nature Happiness, fear of crime, child abuse, attitudes and opinions Composite measures improve upon single item measures by using multiple items to measure one variable Types of composite measures include: Typologies Indexes
Typologies Typologies=Intersection of two or more aspects of the concept(s) you are trying to measure Example 1: Court experience Two issues: Did you serve on a jury? Did you testify as a witness? Which of the following best describes your past court experience? No experience with court Experience as juror only Experience as a witness only Experience as juror and witness
Typologies, Continued Example 2: The research question requires that we measure whether a respondent was a victim of sexual assault and/or a victim of domestic violence You can ask two different items: Have you ever been a victim of sexual assault? Have you ever been a victim of domestic violence? Or you can combine responses into one item: Have you ever been a victim of sexual assault and/or domestic violence? Not a victim of either sexual assault or domestic violence Victim of sexual assault Victim of domestic violence Victim of sexual assault and domestic violence
Index Measures Index: Multiple measures are created based on various aspects of the desired variable/concept In this case, the variable you are trying to measure has many different characteristics or aspects. These types of measures are used to increase the accuracy of measuring an attitude, perception, opinion by asking a variety of items related to the desired concept. Together, the responses are considered a reflection of the concept, attitude, perception, or belief.
Index Example #1 Example: Perception of disorder Two dimensions required to adequately measure the concept: Extent and frequency of the problem Two sets of questions: 1. To what extent do you think graffiti is a problem in your neighborhood? Loitering is a serious problem Loitering is a somewhat serious problem Loitering is a little bit of a problem Loitering is not a problem at all 2. How often do you see graffiti in your neighborhood? All of the time Some of the time Rarely None of the time
Index Example #2 For example: Delinquency Instead of using one item such as, “Have you ever committed delinquency?” you would provide a list of characteristics and use them collectively (a sum) to measure delinquency Have you done any of the following in the past __? Gotten into a serious fight?N Y Taken something worth over $50?N Y Taken a car without permissionN Y Damaged property on purpose?N Y And so on…
Index Example #3 Example: Self-Control Please read each of the following items and indicate the extent to which you agree with each item. I will often say whatever comes into my head without thinking first. Strongly agree Somewhat agree Neither agree or disagree Somewhat disagree Strongly disagree I enjoy working problems slowly and carefully. Often, I don’t spend enough time thinking over a situation before I act. Responses are summed to create a score that relates to high or low levels of self-control.
Assessing the Quality of Your Measures Reliability—Will your measure, if applied repeatedly to the same object, yield the same result each time? Test-retest—same person takes test at two different times Interrater—two people the code same information Validity—Are you measuring what you say you are measuring? Face validity—common agreement Content validity—degree to which it covers the range of meanings Criterion-related validity—extent to which it matches outcomes of a similar, but different measure