--- imach096d/doc/imach.htm 2002/03/06 18:56:09 1.6 +++ imach096d/doc/imach.htm 2002/03/11 22:26:00 1.10 @@ -1,3 +1,4 @@ + @@ -6,6 +7,13 @@ content="text/html; charset=iso-8859-1"> Computing Health Expectancies using IMaCh + + + + + + @@ -29,7 +37,7 @@ color="#00006A">INEDEUROREVES

Version -0.7, February 2002

+0.71a, March 2002


@@ -58,8 +66,6 @@ color="#00006A">) -
  • ncov=2 Number of covariates in the datafile. The - intercept and the age parameter are counting for 2 - covariates.
  • +
  • ncov=2 Number of covariates in the datafile.
  • nlstate=2 Number of non-absorbing (alive) states. Here we have two alive states: disability-free is coded 1 and disability is coded 2.
  • @@ -349,7 +353,7 @@ line

    Covariates

    Intercept and age are systematically included in the model. -Additional covariates can be included with the command

    +Additional covariates can be included with the command:

    model=list of covariates
    @@ -369,6 +373,19 @@ Additional covariates can be included wi the product covariate*age +

    In this example, we have two covariates in the data file +(fields 2 and 3). The number of covariates is defined with +statement ncov=2. If now you have 3 covariates in the datafile +(fields 2, 3 and 4), you have to set ncov=3. Then you can run the +programme with a new parametrisation taking into account the +third covariate. For example, model=V1+V3 estimates +a model with the first and third covariates. More complicated +models can be used, but it will takes more time to converge. With +a simple model (no covariates), the programme estimates 8 +parameters. Adding covariates increases the number of parameters +: 12 for model=V1, 16 for model=V1+V1*age +and 20 for model=V1+V2+V3.

    +

    Guess values for optimization

    @@ -398,7 +415,8 @@ aij bij

    23 -6.234642 0.022315 -

    or, to simplify:

    +

    or, to simplify (in most of cases it converges but there is no +warranty!):

    12 0.0 0.0
    @@ -407,6 +425,45 @@ aij bij 

    23 0.0 0.0
    +

    In order to speed up the convergence you can make a first run with +a large stepm i.e stepm=12 or 24 and then decrease the stepm until +stepm=1 month. If newstepm is the new shorter stepm and stepm can be +expressed as a multiple of newstepm, like newstepm=n stepm, then the +following approximation holds: +

    aij(stepm) = aij(n . stepm) - ln(n)
    +
    and +
    bij(stepm) = bij(n . stepm) .
    + +

    For example if you already ran for a 6 months interval and +got:
    +

    # Parameters
    +12 -13.390179  0.126133 
    +13  -7.493460  0.048069 
    +21   0.575975 -0.041322 
    +23  -4.748678  0.030626 
    +
    +If you now want to get the monthly estimates, you can guess the aij by +substracting ln(6)= 1,7917
    and running
    +
    12 -15.18193847  0.126133 
    +13 -9.285219469  0.048069
    +21 -1.215784469 -0.041322
    +23 -6.540437469  0.030626
    +
    +and get
    +
    12 -15.029768 0.124347 
    +13 -8.472981 0.036599 
    +21 -1.472527 -0.038394 
    +23 -6.553602 0.029856 
    +
    +which is closer to the results. The approximation is probably useful +only for very small intervals and we don't have enough experience to +know if you will speed up the convergence or not. +
             -ln(12)= -2.484
    + -ln(6/1)=-ln(6)= -1.791
    + -ln(3/1)=-ln(3)= -1.0986
    +-ln(12/6)=-ln(2)= -0.693
    +
    +

    Guess values for computing variances

    This is an output if mle=1. But it can be @@ -485,14 +542,15 @@ prevalences and health expectancies +102. It is possible to get extrapolated stationary prevalence by +age ranging from agemin to agemax.

    -

    Similarly, it is possible to get extrapolated stationary -prevalence by age ranging from agemin to agemax.

    +

    Setting bage=50 (begin age) and fage=100 (final age), makes +the program computing life expectancy from age 'bage' to age +'fage'. As we use a model, we can interessingly compute life +expectancy on a wider age range than the age range from the data. +But the model can be rather wrong on much larger intervals. +Program is limited to around 120 for upper age!

    +

    From the population file, we estimate the number of people in +each state. At age 73, 645857 persons are in state 1 and 69320 +are in state 2. One year latter, 512892 are still in state 1, +85003 are in state 2 and 117282 died before 1/1/1990.

    +
    -

    Trying an example

    +

    Trying an example

    Since you know how to run the program, it is time to test it on your own computer. Try for example on a parameter file named Enter the parameter fi - @@ -1138,8 +1248,8 @@ simple justification (name, email, insti href="mailto:brouard@ined.fr">mailto:brouard@ined.fr and mailto:lievre@ined.fr .

    -

    Latest version (0.7 of February 2002) can be accessed at http://euroreves.ined.fr/imach
    +

    Latest version (0.71a of March 2002) can be accessed at http://euroreves.ined.fr/imach

    IMACH, Version 0.7

    Enter +

    IMACH, Version 0.71

    Enter the parameter file name: ..\mytry\imachpar.txt