Convergence Issue: Multilevel Mediation Model with Categorical Exogenous Variable

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Riley Hess

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Sep 9, 2021, 1:06:29 PM9/9/21

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Hello,

I am trying to run a multilevel mediation model in lavaan with a categorical independent variable, but am running into convergence issues. There are three dummy-coded independent variables (d1, d2, d3), one continuous mediator (admiration), and one continuous dependent variable (activefac). Observations are clustered within participants.

When I run this model as a single level mediation model I don't get any errors. There are 1381 observations and 179 clusters.

Please let me know if any additional information is needed. Thank you!

Best,

Riley

Here is the model syntax:

mediation1 <- '

level:1

activefac~ b*admiration + c1*d1 + c2*d2 + c3*d3

admiration~a1*d1 + a2*d2 + a3*d3

#indirect and total effects

ab1:=a1*b

ab2:=a2*b

ab3:=a3*b

total1 := c1 + (a1 * b)

total2 := c2 + (a2 * b)

total3 := c3 + (a3 + b)

level:2

admiration ~~ admiration + d1 + d2 + d3

d1 ~~ d2 + d3

d2 ~~ d3

mediation1out <- sem(mediation1, datalong, cluster = "participantID", estimator = "MLR")

And here are the errors and warnings:

Warning messages:

1: In lav_data_full(data = data, group = group, cluster = cluster, :

lavaan WARNING:

Level-1 variable “activefac” has no variance within some clusters.

The cluster ids with zero within variance are: 102 123 160 166

2: In lav_data_full(data = data, group = group, cluster = cluster, :

lavaan WARNING:

Level-1 variable “admiration” has no variance within some

clusters. The cluster ids with zero within variance are: 2 5 6 7

18 32 37 38 45 57 59 61 63 64 66 67 70 76 93 97 98 108 129 134 145

162 163 166 167 168 169 170 173 174 176 35

3: In lav_data_full(data = data, group = group, cluster = cluster, :

lavaan WARNING:

Level-1 variable “d1” has no variance within some clusters. The

cluster ids with zero within variance are: 101

4: In lav_data_full(data = data, group = group, cluster = cluster, :

lavaan WARNING:

Level-1 variable “d2” has no variance within some clusters. The

cluster ids with zero within variance are: 85 88 94 117 141 148

179 65 101

5: In lav_data_full(data = data, group = group, cluster = cluster, :

lavaan WARNING:

Level-1 variable “d3” has no variance within some clusters. The

cluster ids with zero within variance are: 123 35 101

6: In lavaan::lavaan(model = mediation1, data = datalong, cluster = "participantID", :

lavaan WARNING:

the optimizer warns that a solution has NOT been found!

7: In lavaan::lavaan(model = mediation1, data = datalong, cluster = "participantID", :

lavaan WARNING: estimation of the baseline model failed.

Screen Shot 2021-09-09 at 1.05.06 PM.png

Terrence Jorgensen

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Sep 17, 2021, 5:46:19 PM9/17/21

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When I run this model as a single level mediation model I don't get any errors.

You don't have any restrictions on your Level-2 model. Why don't you just fit the single-level model and specify cluster= so you get cluster-robust SEs?

Terrence D. Jorgensen

Assistant Professor, Methods and Statistics

Research Institute for Child Development and Education, the University of Amsterdam