What is the difference between a construct and a measure

Next, a panel of judges is recruited to select specific items from this candidate pool to represent the construct of interest. Judges may include academics trained in the process of instrument construction or a random sample of respondents of interest i.

The selection process is done by having each judge independently rate each item on a scale from 1 to 11 based on how closely, in their opinion, that item reflects the intended construct 1 represents extremely unfavorable and 11 represents extremely favorable. For each item, compute the median and inter-quartile range the difference between the 75 th and the 25 th percentile — a measure of dispersion , which are plotted on a histogram, as shown in Figure 6.

The final scale items are selected as statements that are at equal intervals across a range of medians. This can be done by grouping items with a common median, and then selecting the item with the smallest inter-quartile range within each median group.

However, instead of relying entirely on statistical analysis for item selection, a better strategy may be to examine the candidate items at each level and selecting the statement that is the most clear and makes the most sense. The median value of each scale item represents the weight to be used for aggregating the items into a composite scale score representing the construct of interest.

We now have a scale which looks like a ruler, with one item or statement at each of the 11 points on the ruler and weighted as such. Because items appear equally throughout the entire pointrange of the scale, this technique is called an equal-appearing scale.

Thurstone also created two additional methods of building unidimensional scales — the method of successive intervals and the method of paired comparisons — which are both very similar to the method of equal-appearing intervals, except for how judges are asked to rate the data. For instance, the method of paired comparison requires each judge to make a judgment between each pair of statements rather than rate each statement independently on a 1 to 11 scale.

Hence, the name paired comparison method. With a lot of statements, this approach can be enormously time consuming and unwieldy compared to the method of equal-appearing intervals. The Likert method, a unidimensional scaling method developed by Murphy and Likert , is quite possibly the most popular of the three scaling approaches described in this chapter. These items are then rated by judges on a 1 to 5 or 1 to 7 rating scale as follows: 1 for strongly disagree with the concept, 2 for somewhat disagree with the concept, 3 for undecided, 4 for somewhat agree with the concept, and 5 for strongly agree with the concept.

Following this rating, specific items can be selected for the final scale can be selected in one of several ways: 1 by computing bivariate correlations between judges rating of each item and the total item created by summing all individual items for each respondent , and throwing out items with low e. Hence, this method is called a summated scale. Note that any item with reversed meaning from the original direction of the construct must be reverse coded i.

The idea is that people who agree with one item on this list also agree with all previous items. In practice, we seldom find a set of items that matches this cumulative pattern perfectly. A scalogram analysis is used to examine how closely a set of items corresponds to the idea of cumulativeness. Like previous scaling methods, the Guttman method also starts with a clear definition of the construct of interest, and then using experts to develop a large set of candidate items.

The resulting matrix will resemble Table 6. Notice that the scale is now almost cumulative when read from left to right across the items. However, there may be a few exceptions, as shown in Table 6. To determine a set of items that best approximates the cumulativeness property, a data analysis technique called scalogram analysis can be used or this can be done visually if the number of items is small.

Y indicates exceptions that prevents this matrix from being perfectly cumulative. An index is a composite score derived from aggregating measures of multiple constructs called components using a set of rules and formulas. It is different from scales in that scales also aggregate measures, but these measures measure different dimensions or the same dimension of a single construct. A well-known example of an index is the consumer price index CPI , which is computed every month by the Bureau of Labor Statistics of the U.

Department of Labor. Each month, government employees call all over the country to get the current prices of more than 80, items. Using a complicated weighting scheme that takes into account the location and probability of purchase of each item, these prices are combined by analysts, which are then combined into an overall index score using a series of formulas and rules.

This index is a combination of three constructs: income, education, and occupation. Income is measured in dollars, education in years or degrees achieved, and occupation is classified into categories or levels by status. However, SES index measurement has generated a lot of controversy and disagreement among researchers. The process of creating an index is similar to that of a scale. First, conceptualize define the index and its constituent components. Though this appears simple, there may be a lot of disagreement among judges on what components constructs should be included or excluded from an index.

Second, operationalize and measure each component. For instance, how will you categorize occupations, particularly since some occupations may have changed with time e. Third, create a rule or formula for calculating the index score. Again, this process may involve a lot of subjectivity. Lastly, validate the index score using existing or new data. Though indexes and scales yield a single numerical score or value representing a construct of interest, they are different in many ways. To work with your constructs, you must establish a connection between them and the concrete reality in which you live.

This process is called operationalization. Your operational definitions describe the variables you will use as indicators and the procedures you will use to observe or measure them. You need an operational definition because you can't measure anything without one, no matter how good your conceptual definition might be. Why can't you skip the conceptual definition and use only an operational definition to define your concept?

A conceptual definition tells you what the concept means, while operational definitions only tell you how to measure it. If you have only an operational definition, you may know how to measure it, but you won't know what you are measuring. This means that your measurements won't be worth much, considering that you don't know what the concept is, so you don't know what you measured.

A concept defined only operationally may make a nice little ceremony as you carry out the steps described by the operational definition, but it doesn't mean anything and it is not related to other concepts.

A conceptual definition tells you what the concept means, while an operational definition only tells you how to measure it. A conceptual definition tells what your constructs are by elplaining how they are related to other constructs. This explanation and all of the constructs it refers to are abstract. On the other hand, your operational definitions describe the variables you will use as indicators for youor constructs and the procedures you will use to observe or measure the variables.

A professor is studying learning and academic performance and uses GPA as a measure of how much her students have learned. Discuss why or why not this is an adequate operational definition of learning.

In order to evaluate this operational definition, it would be useful to know what it means to "learn" something. Is it necessary to memorize the material? Some constructs are relatively simple like political party affiliation and can be measured using only one or a few questions, while other constructs are more complex such as employee satisfaction and may require [Page ] a whole battery of questions to fully operationalize the construct to suit the end user's needs.

Complex constructs contain multiple dimensions or facets that are bound together by some commonality that, as a whole, compose the construct. Without clearly conceptualizing the construct's dimensions and the common theme binding the dimensions together, the survey developer runs the risk of either creating a set of questions that does Show page numbers Download PDF. Second, the levels of measurement can serve as a rough guide to the statistical procedures that can be used with the data and the conclusions that can be drawn from them.

With nominal-level measurement, for example, the only available measure of central tendency is the mode. Also, ratio-level measurement is the only level that allows meaningful statements about ratios of scores.

One cannot say that someone with an IQ of is twice as intelligent as someone with an IQ of 70 because IQ is measured at the interval level, but one can say that someone with six siblings has twice as many as someone with three because number of siblings is measured at the ratio level.

The assignment of scores to individuals where the scores represent some characteristic of the individuals. A definition of a psychological construct that describes the behaviours and internal processes of that construct and how it relates to other variables. Level of measurement used for categorical variables and involves assigning scores that act as category labels. Level of measurement in which scores represent the rank order of the individuals, showing how individuals are different from each other and whether they are higher or lower on the variable being measured.

Level of measurement in which scores represent the precise magnitude of the difference between individuals, but a score of 0 does not represent an absence of the characteristic. Level of measurement in which there is a true zero point that represents the complete absence of the characteristic. Skip to content Chapter 5: Psychological Measurement. Define measurement and give several examples of measurement in psychology.

Explain what a psychological construct is and give several examples. Distinguish conceptual from operational definitions, give examples of each, and create simple operational definitions.

Distinguish the four levels of measurement, give examples of each, and explain why this distinction is important. Psychological measurement can be achieved in a wide variety of ways, including self-report, behavioural, and physiological measures. Psychological constructs such as intelligence, self-esteem, and depression are variables that are not directly observable because they represent behavioural tendencies or complex patterns of behaviour and internal processes.

An important goal of scientific research is to conceptually define psychological constructs in ways that accurately describe them. For any conceptual definition of a construct, there will be many different operational definitions or ways of measuring it.

The use of multiple operational definitions, or converging operations, is a common strategy in psychological research. Variables can be measured at four different levels—nominal, ordinal, interval, and ratio—that communicate increasing amounts of quantitative information. The level of measurement affects the kinds of statistics you can use and conclusions you can draw from your data.

Practice: Think of three operational definitions for sexual jealousy, decisiveness, and social anxiety. Consider the possibility of self-report, behavioural, and physiological measures. Be as precise as you can.

Practice: For each of the following variables, decide which level of measurement is being used. An university instructor measures the time it takes her students to finish an exam by looking through the stack of exams at the end. She assigns the one on the bottom a score of 1, the one on top of that a 2, and so on. Participants in a research study are asked whether they are right-handed or left-handed.

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