Binary models 2

1
Binary models 2

• LCGA model of frequent bedwetting
• tests of gender invariance

2
Latent Class Growth Analysis

• Alternative to LLCA
• More parsimonius than LLCA
• Unlikely to capture some shapes e.g. relapse
• Fits polynomials on logit scale, not in
  probability space (more flexible than one might
  think)

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The data frequent wetting
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The plan

• Fit LLCA and LCGA models of the following
• model frequent bedwetting on boys and girls
  separately
• Combine dataset and fit variant model with
  KNOWNCLASS
• Test for gender invariance by constraining
  parameters across gender groups

5
Sex specific models
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LLCA results
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Fitting LCGA model

• variable
• ltsnipgt
• classes c (3)
• useobservations (sex 1)
• analysis
• ltsnipgt
• model
• OVERALL
• I S Q nwet_1_at_0 nwet_2_at_1 nwet_3_at_2 nwet_4_at_3
  nwet_5_at_5

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Sex specific models
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LCGA / LLCA comparison
LLCA LCGA
Shapes v similar Parameters LLCA (17) versus
LCGA (11) LCGA BICs lower than LLCA
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Fitting LCGA KNOWNCLASS model

• variable
• ltsnipgt
• classes sex (2) c (3)
• knownclass sex (kz021 1 kz021 2)
• analysis
• ltsnipgt
• model
• OVERALL
• I S Q nwet_1_at_0 nwet_2_at_1 nwet_3_at_2 nwet_4_at_3
  nwet_5_at_5

11
LCGA knownclass results
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LCGA Invariant model

• model
• OVERALL
• I S Q nwet_1_at_0 nwet_2_at_1 nwet_3_at_2 nwet_4_at_3
  nwet_5_at_5
• c on sex
• sex1.c1 sex2.c1
• i (1) i (1)
• s (11) s (11)
• q (111) q (111)
• sex1.c2 sex2.c2
• i (2) i (2)
• s (22) s (22)
• q (222) q (222)
• sex1.c3 sex2.c3
• i (3) i (3)

13
LCGA knownclass results
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LCGA knownclass Invariant
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LLCA knownclass Invariant

• OVERALL
• c on sex
• sex1.c1
• NWET_KK41 (1)
• NWET_KM41 (2)
• NWET_KP41 (3)
• NWET_KR41 (4)
• NWET_KU41 (5)
• sex2.c1
• NWET_KK41 (1)
• NWET_KM41 (2)
• NWET_KP41 (3)
• NWET_KR41 (4)
• NWET_KU41 (5)

sex1.c2 NWET_KK41 (11)
NWET_KM41 (12) NWET_KP41 (13)
NWET_KR41 (14) NWET_KU41 (15)
sex2.c2 NWET_KK41 (11)
NWET_KM41 (12) NWET_KP41 (13)
NWET_KR41 (14) NWET_KU41 (15)
sex1.c3 NWET_KK41 (21)
NWET_KM41 (22) NWET_KP41 (23)
NWET_KR41 (24) NWET_KU41 (25)
sex2.c3 NWET_KK41 (21)
NWET_KM41 (22) NWET_KP41 (23)
NWET_KR41 (24) NWET_KU41 (25)
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LCGA/LLCA Invariant results
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Summary

• LCGA is a possible, more parsimonius alternative,
  to LLCA when trajectory shapes are well-behaved
• One should approach an invariant model via
  individual models before combining data within a
  parameter variant knownclass model