How to Compute for the Construct Mean and Standard Deviation in SPSS

 

What is a construct?

• In the context of survey research, a construct is an abstract idea, underlying theme, or subject matter that one wishes to measure using survey questions. As a cohesive set, the dimensions of a construct define the construct. Some constructs are relatively simple and do not have many dimensions [1]. Structural equation models are often used to assess unobservable 'latent' constructs [2]. Examples are from the theory of planned behavior (TPB) but modified in the context of purchasing organic rice.

Computing for the construct mean in every case

Step-by-step procedure:

• First, you need to compute the mean of the construct’s items in every case (see above).

1. In SPSS, go to Transform — Compute variable.
• A window will pop-out 'Compute Variable'.
2. Do the following in the 'Compute Variable' window:
• In the target variable box, type the name of the variable as MEAN_ATT, for example for mean for attitude variable.
• In the numeric expression box, do the manual computation by throwing in the item and using the given calculator buttons — Click OK.
• (ATT_1 + ATT_2 + ATT_3) / 3 for example for Attitude construct which has 3 items.
3. Go to the 'Variable View' and you will see the new variables created there.
• Do these steps with one construct at a time.
• Examples of these variables and items are shown below.

Constructs and measurement items from TPB modified in the context of organic food consumption

• Second, compute for the overall construct mean and SD using the newly computed variables.
1. In SPSS, go to Analyze — Descriptive statistics — Frequencies.
• A window will pop-out 'Frequencies'.
2. Do the following in the 'Frequencies' window:
• Throw in the new variables.
• Click the statistics button.
• A window will pop-out 'Frequencies: Statistics'.
3. In the 'Frequencies: Statistics' window:
• Check for Mean (Central Tendency section) and Std. deviation (Dispersion section) — click Continue.
4. Click Ok
• You will see the result in the 'Statistics' section of the output.

Computing for the overall mean and SD

Results generated from the output window

Hope this helps. :)