How to Fit a Structural Equation Model in Displayr

Step 1: Load the data

Typically, data sets are loaded into Displayr from raw data files. In this case, we will load data from an R package.

1. Go to Data Sources > Plus (+) > R.
2. Under Name, enter the name BollenPoliticalDemocracy for the data set.
3. Paste the code below into the R Code box and click OK.

library(sem)
Bollen

Step 2: Fit the model

The hard step is fitting the model, which requires specifying the measurement model, the relationships to be tested (i.e., the regressions), and the model's correlation structure. For more information, please check out the lavaan website.

To do this:

1. From the toolbar, select Calculation > Custom Code.
2. Click on the page to place the calculation object.
3. Paste in the code below in the R Code window and click Calculate in the object inspector .

# Load the package for computing the SEM
library(lavaan)

# Describe the model
model <- '
    #measurement model
        ind60 =~ x1 + x2 + x3
        dem60 =~ y1 + y2 + y3 + y4
        dem65 =~ y5 + y6 + y7 + y8
    #regressions
        dem60 ~ ind60
        dem65 ~ ind60 + dem60
    #residual corrections
        y1 ~~ y5
        y2 ~~ y4 + y6
        y3 ~~ y7
        y4 ~~ y8
        y6 ~~ y8'

# Assemble the raw data into a data frame, using the variable names
# from the raw data
df = data.frame(y1, y2, y3, y4, y5, y6, y7, y8, x1, x2, x3)

# Fit the model
fit <- sem(model, data = df)

The output will appear as:

Step 3: Review the path diagram

To check that the model has been correctly specified, it's a good idea to review the path diagram.

1. From the toolbar, select Calculation > Custom Code.
2. Click on the page to place the calculation object.
3. Paste in the code below and click Calculate from the object inspector .

library(semPlot)
semPaths(fit)

The output will appear as:

Step 4: Extract the summary statistics

1. From the toolbar, select Calculation > Custom Code.
2. Click on the page to place the calculation object.
3. Paste in the code below and click Calculate from the object inspector .
4. To align the text neatly, go to object inspector > Appearance > Appearance > Font and set the font to Courier New.

summary(fit)

The output will appear as:

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