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help for ^sf36^                                      ver 2.2.2 Sept 21, 1999
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Calculation of summary statistics for the SF-36 Health Survey Instrument
------------------------------------------------------------------------

 ^sf36^ [^if^ exp] [^in^ range] ^, natver^(country abbrev)
                            [^stub^(variable prefix)  ^by^(groupvars)
                             ^check^ | ^nocheck^
                             ^var^lab | ^novar^lab
                             ^val^lab | ^noval^lab ]

where:

  (i)  ^if^ and ^in^ define valid observations for the command.

 (ii)  ^natver^ requires a string argument specifying the country in
         which the data were collected. This is necessary if you wish
         to calculate the ^SUMMARY PHYSICAL HEALTH^ and ^SUMMARY MENTAL^
         ^HEALTH^ measures in addition to the 8 "traditional" SF-36
         measures. The two Summary measures require intermediate data
         (means, standard deviations, and factor scores) specific to
         each country and usually derived from large national surveys.
         The allowed ^country abbrev^s are: ^AUS US UK^.

(iii)  ^stub^ requires a ^variable prefix^ to be specified. This is the
         common prefix of the 36 variables. If not specified ^sf36^
         assumes that your variables have the prefix ^SF36_^. The prefix
         is a string whose length must not exceed 5.

 (iv)  ^check^ implements "manual" range checking. Out-of range data
         cause informative messages to be displayed, with the current
         observation number and value of each out-of-range value. The
         program then terminates, giving the user the opportunity to
         check and edit data before reinvoking the program.
       ^nocheck^ (default, equivalent to not specifying this option)
         implements "automatic" data recoding if out-of-range data
         are detected. Out-of-range data are set to missing and ^sf36^
         continues execution.

  (v)  ^var^lab specifies that the ^original^ 36 variables are given
         variable labels defined within the program. Pre-existing
         labels in the data are overwritten. These labels follow the
         documentation of the SF-36 Australian version. The setting
         of ^natver^ does not alter this.
       ^novar^lab (default, equivalent to not specifying this option)
          prevents any new variable labels being applied to the data.

 (vi)  ^val^lab specifies that the ^original^ 36 variables are given
         value labels defined within the program. Pre-existing
         labels in the data are overwritten. These labels follow the
         documentation of the SF-36 Australian version. The setting
         of ^natver^ does not alter this.
       ^noval^lab (default, equivalent to not specifying this option)
         prevents any new value labels being applied to the original
         variables.

       New variables generated by ^sf36^ are given pre-defined
       variable and value labels regardless of the status of the
       ^var^lab and ^val^lab options.



Description
-----------

^sf36^ is a program for processing SF-36 data using Stata.  The SF-36
is a general-purpose health survey instrument published by the Medical
Outcomes Trust. It is comprised of 36 questions in 8 domains. In
addition, if national weighting data are available, two summary
measures (PHYSICAL HEALTH and MENTAL HEALTH) may be calculated.


What you need:
-------------

You need a Stata data set with 36 variables corresponding to the 36
questions of the SF-36. You may, of course, have additional variables,
for example, a case identifier and other demographic variables.

The 36 SF-36 question variables ^must^ be named in accordance with
the following rule:

Variables in the data set must be named ^<stub>nn$^  where:

  ^<stub>^  is the common variable prefix specified as the argument of
              the ^stub^ option; if not specified, "SF36_" is assumed;
      ^nn^  is the question number given as 2 digits (01 to 11); and
       ^$^  is the question part, if any, for example, a b c etc....

  Examples:  SF36_03j     SF36_05a
             quest04c     quest09b
             SFQ11a       SFQ10

Important note: The UK version is based on "The UK SF36: An analysis
--------------  and interpretation manual" Jenkinson et al, Health
                Services Research Unit, Oxford 1996.  This version
                changes the original numbering of the US SF36 such
                that:

           US                         UK
           --                         --
           question  10      ==>      question  9j
           questions 11a-d   ==>      questions 10a-d

           Also a goodly number of changes are made to the scoring
           algorithm (cf. MOT SF36 Health Survey Scoring Manual).
           All these changes are dealt with in ^sf36.ado^.
           However, ^sf36.ado^ expects that UK data sets already
           have data scored as in pages 49-51 of Jenkinson.  Unlike
           the US and Australian case, ^sf36.ado^ does not do any
           recoding. This is because the UK SF36 instrument does not
           have specified raw data values associated with responses,
           but simply ticked boxes which are presumably scored according
           to Jenkinson's algorithm at the time of initial data entry.


What you get: (assume the stub is the default "SF36_")
------------

First, ^sf36^ implements range checking according to rules specified
in the SF-36 Reference and Scoring Manual. (See the ^check^ option).

Next, depending on the status of the ^var^lab and ^val^lab options the
program labels the 36 original variables. It does so according to the
Australian version of the SF-36.  (There are trivial semantic
differences between countries.)

Value labels are named as ^lab_nn(nn)^, for example, lab_11 is the
common value label for 4 variables SF36_11(a,b,c,d), and lab_0405
is the common value label for 7 variables SF36_04(a,b,c,d) and
SF36_05(a,b,c).

Then the program handles missing data using either means of
non-missing items or by coding the entire scale as missing for
that subject as prescribed in the SF-36 documentation.

57 new variables appear in the data set (the original SF36_nn$
variables are untouched).  The 57 comprise:

36 new variables (named ^tx_nn$^) represent the original data
with missing data imputed by mean substitutions or by missing values
substituted for each item in a scale (as specified in the SF-36 docs).

8 new variables represent the untransformed scale scores.

1 new variable for the Health Transition scale (a copy of SF36_02)

8 new variables represent the corresponding transformed scores.

4 new variables associated with the PHYSICAL HEALTH and MENTAL HEALTH
  SUMMARY scores.  These are:

   2 new variables representing the raw factor scores: raw_PHYS,
     raw_MENT (also called AGGregated scores in the SF-36 docs.)
   2 new variables representing the standardised scores: std_PHY,
     std_MENT (also called the transformed scores, PCS and MCS, in
     the SF-36 docs)


Calculation of these last 4 variables requires nation-specific data
hard-coded into ^sf36.ado^. See discussion of national versions below.

The new variables are:

  tx_nn$      (nn = 01 to 11; $ = a...j as appropriate)

  PF          Physical Functioning
  RP          Role Functioning Physical
  RE          Role Functioning Emotional
  MH          Mental Health
  VT          Vitality
  BP          Bodily Pain
  GH          General Health
  SF          Social Functioning

  HT          reported Health Transition

  PF_trans    Physical Function-transformed
  RP_trans    Role Physical-transformed
  RE_trans    Role Emotional-tranformed
  MH_trans    Mental Health-transformed
  VT_trans    Vitality-transformed
  BP_trans    Bodily Pain-transformed
  GH_trans    General Health-transformed
  SF_trans    Social Function-transformed

  raw_PHYS    raw factor score (aggregated) for Physical Health
  raw_MENT    raw factor score (aggregated) for MentalHealth
  std_PHYS    Summary standardised Physical Health/PCS
  std_MENT    Summary standardised Mental Health/MCS

^sf36^ issues three ^summarize^ commands: the first gives
summary statistics for the untransformed scales, the second gives
them for the transformed scales, and the third gives them for the
4 physical and mental health summary variables (if data are available).

Finally, the program writes a ^note^ to the dataset in memory
warning that new variables generated by ^sf36^ were done so
according to the current ^if^ and ^in^ conditions. This warning
is echoed to the display. The original 36 variables are
unchanged.

National data
-------------

US data are documented in "SF-36 Physical & Mental Health Summary
Scales: A user's manual"  Ware, Health Assessment Lab 1994.

Australian data are from the 1995 National Health Survey, Australian
Bureau of Statistics.

UK data are from the OHLS as documented in "The UK SF36: an analysis
and interpretation manual" Jenkinson et al, Dept Primaty Care and
Public Health Oxford 1996 (and errata page).

Examples
--------

Variables have prefix "SF36_"; out-of-range values handled manually;
Australian data to be used for PHYSICAL and MENTAL HEALTH summary
statistics; program supplies variable labels and value labels;
summary statistics are produced for all data combined and for each of
the states of the Commonwealth:


 . ^sf36^ ^using^ mydata, ^check^ ^var^ ^val^ ^natver^(AUS) ^by^(state)

Variables have prefix "sf36Q"; out-of-range values handled
automatically; US data to be used for PHYSICAL and MENTAL
HEALTH summary statistics; program does not label original 36
variables; new variables and summary statistics only on males:

 . ^sf36^ ^using^ mysf36 ^if^ sex=="M", ^stub(^sf36Q^)^ ^natver(^US^)^

Variables have prefix "SF36_"; out-of-range values handled
automatically; program supplies value labels, but not
variable labels; Australian data used for Summary scales:

 . ^sf36^ ^using^ sf36test, ^nocheck^ ^val^ ^natver^(AUS)

(screen output now follows:)

^Note^
^----^
All new variables in the data set were constructed under the qualifiers:
   if: ^no if condition^
   in: ^no in condition^
Observations on the new variables not satisfying these criteria will be
set to missing. Observations on original ^SF36_nn$^ vars are unchanged.
A ^note^ to this effect has been  written to the data in memory.


^Raw scale statistics^
^--------------------^

Variable |     Obs        Mean   Std. Dev.       Min        Max
---------+-----------------------------------------------------
      PF |      99    25.15869    5.01538         11         30
      RP |      93    6.319032   1.621805          4          8
      BP |      98        8.95   2.508881          2         12
      GH |      96    16.91187   4.572607          6         25
      VT |     100       15.25   3.851968          7         23
      SF |     100        8.68   1.979083          3         10
      RE |      92    5.173913   1.173037          3          6
      MH |     100     23.5975   4.876492          7         30
      HT |      96     2.53125   .9509344          1          4

^Transformed scale statistics^
^----------------------------^

Variable |     Obs        Mean   Std. Dev.       Min        Max
---------+-----------------------------------------------------
PF_trans |      99    75.79343    25.0769          5        100
RP_trans |      93    57.97581   40.54513          0        100
BP_trans |      98        69.5   25.08881          0        100
GH_trans |      96    59.55937   22.86304          5        100
VT_trans |     100       56.25   19.25984         15         95
SF_trans |     100        83.5   24.73853       12.5        100
RE_trans |      92    72.46377   39.10123          0        100
MH_trans |     100       74.39   19.50597          8        100

Summary PHYSICAL & MENTAL HEALTH scale statistics (AUS)
    raw factor scores and standardised scores
-------------------------------------------------------

Variable |     Obs        Mean   Std. Dev.       Min        Max
---------+-----------------------------------------------------
raw_PHYS |      88   -.4216362   1.106496  -3.286022    1.81991
raw_MENT |      88   -.1788276   1.118642  -4.008066   1.352772
std_PHYS |      88    45.78364   11.06496   17.13978    68.1991
std_MENT |      88    48.21172   11.18642   9.919338   63.52772


Author
------

Philip Ryan
Department of Public Health,
University of Adelaide, South Australia
pryan@@medicine.adelaide.edu.au


