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Table 2 Mixed effects logistic model* for estimating the percentage of women receiving periodic mammograms by age and cohort of birth

From: Dissemination of periodic mammography and patterns of use, by birth cohort, in Catalonia (Spain)

Fixed effects
Parameter Value Standard error p-value
ϕ 1(Asym) 0.968 0.065 < 0.001
ϕ 2(xmid) 45.004 3.091 < 0.001
ϕ 3(scal) 5.384 0.640 < 0.001
Random effects
Parameter Standard deviation Residual  
ϕ 1(Asym) NS   
ϕ 2(xmid) 6.697 0.002  
ϕ 3(scal) NS   
Random effect for parameter ϕ 2 ( xmid ) by cohort of birth
Cohort of birth Random effect ** Fixed plus random ***  
1938–1942 11.771 56.78  
1943–1947 5.193 50.20  
1948–1952 -0.244 44.76  
1953–1957 -3.883 41.12  
1958–1962 -5.160 39.84  
1963–1967 -7.677 37.33  
  1. NS: Not significant.
  2. * The model is:
  3. p = ϕ 1 1 + e x p [ ( ϕ 2 a g e ) / ϕ 3 ] MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGaciGaaiaabeqaaeqabiWaaaGcbaGaemiCaaNaeyypa0tcfa4aaSaaaeaacqaHvpGzdaWgaaqaaiabigdaXaqabaaabaGaeGymaeJaey4kaSIaemyzauMaemiEaGNaemiCaaNaei4waSLaeiikaGIaeqy1dy2aaSbaaeaacqaIYaGmaeqaaiabgkHiTiabdggaHjabdEgaNjabdwgaLjabcMcaPiabc+caViabew9aMnaaBaaabaGaeG4mamdabeaacqGGDbqxaaaaaa@4774@ were p indicates the percentage of women receiving periodic mammograms, ϕ 1 (asym) is the horizontal asymptote as age increases or the percentage at which the curve levels off, ϕ 2 (xmid) indicates the age value at which approximately half of the population is receiving periodic mammograms and ϕ 3 (scal) indicates the difference in years between the age at which 3/4 of the population is receiving periodic mammograms and the age ϕ 2.
  4. (**) The values indicate the departure from the fixed effect (45.0 years of age) for each cohort of birth. (***): The values can be interpreted as the age at which approximately 50% of the women will be receiving periodic mammograms.
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