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2. LCA General Description. People (or objects) from a heterogeneous population assumed to belong to a limited number of homogeneous groups referred to as latent classes"Latent classes are categories of a latent variable, each one of which contains individuals who are similar to each other and di
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1. 1 LCA General Description Statistical method for finding subtypes of related cases from multivariate categorical data
LCA concerned with the structure of cases (i.e., the latent taxonomic structure)
person-centered
differs from factor analysis which is concerned with the structure of variables
similar to cluster analysis, but is based on probabilistic theory
2. 2 LCA General Description People (or objects) from a heterogeneous population assumed to belong to a limited number of homogeneous groups referred to as “latent classes”
Latent classes are categories of a latent variable, each one of which contains individuals who are similar to each other and different from individuals in other categories
3. 3 Good examples of LCA Patterns of cigarette smoking(Chen et al., 2004)
General substance use(Flaherty, 2002)
Grouping cancer patients by psychosocial needs(Soothill, 2004)
Types of infant temperament(Loken, 2004)
Attention-deficit/hyperactivity typology(Neuman et al., 1999)
Eating disorder phenotypes(Keel et al., 2004)
Subtypes of depression(Parker et al., 1999)
Structure of psychosis (Kendler et al., 1998)
Metabolic control(Seiffge-Krenke & Stemmler, 2003)
4. 4 What would the data look like?
5. 5 kp ? 23 = 8 Possible Response Patterns
6. 6 Purpose of LCA Use patterns of responses to observed categorical variables to:
identify the number of underlying classes
classify each individual into one class and
determine class size
7. 7 How LCA Works There are 2 primary model parameters
the prevalence of each case in a class (latent class probabilities; LCP)
e.g., the proportion of individuals in "disease present" vs. "disease absent" latent classes
conditional response probability (CRP)
the probability that an individual within a particular class will respond "present" or "yes" to a target item
e.g., the probability for each symptom (item) within a latent class being present
8. 8 The LCA Model Observed Categorical Items (u’s) Categorical Latent Class Variable (c) Continuous or Categorical Covariates (x)