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help for pnrcheck 
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pnrcheck

    pnrcheck variable_pnr [, savepnr(variable_name) saveind(variable_name)
        listwrong listmissing display ]

Description

    pnrcheck Algorithm to verify the check digit in Swedish personal
        identification numbers (PNRs).  The check digit is the tenth digit
        constructed from the preceding nine digits, according to date of
        birth and gender.

Remark

    The variable_pnr could be either a string (A) or a numeric variable (B).
        The check digit could also be missing (C). See help datatypes.

(A) The variable_pnr could be stored as string

    Case 1 "4102179704" str10 (standard storage type)
    Case 2 "194102179704" str12 (if there are 2 initial numbers of the year)
    Case 3 "410217-9704" str11 (if there is a minus sign)
    Case 4 "19410217-9704" str13 (if there is a minus sign and the 2 initial
        numbers of the year)

(B) The variable_pnr could be stored as number with double precision

    Case 5 4.102e+09 double (corresponding to Case 1)
    Case 6 1.914e+11 double (corresponding to Case 2)

(C) The tenth digit or check digit of the variable_pnr could be missing

    Case 7 4.102e+08 double (Case 5 without the check digit)
    Case 8 "410217970" str9 (Case 1 without the check digit)

Algorithm

    STEP 1 Multiply each of the first nine digits in the PNR by the digits
        2,1,2,1,2,1,2,1,2

    STEP 2 Calculate the cumulative sum of each of these 9 calculations

    STEP 3 Verify if the check digit of variable_pnr is equal to the number
        we would have to add to the cumulative sum (from STEP 2) to obtain a
        multiple of 10

Options

    savepnr(variable_name) saves the right PNR variable

    saveind(variable_name) saves an indicator variable according to the check
        digit status (0=Right, 1=Wrong, 2=Missing)

    display displays algorithm's results: number of wrong and right PNR,
        percentage

    listwrong lists temporary variables input_pnr i_check output_pnr o_check
        only for individuals whose check digit is wrong

    listmissing lists temporary variables input_pnr i_check output_pnr
        o_check only for individuals whose check digit is missing

Examples

    . insheet using
        http://nicolaorsini.altervista.org/stata/tutorial/p/ex_pnrs.txt,
        clear
    . pnrcheck pnr
    . pnrcheck pnr, savep(pnrright) di
    . pnrcheck pnr, savep(pnrright) savei(indvar) di listw
        

Authors      

    Nicola Orsini, I.M.M., Karolinska Institutet, Sweden
    Nicholas J. Cox, University of Durham, U.K.
    Rino Bellocco, M.E.B., Karolinska Institutet, Sweden

Support

    Nicola Orsini, http://nicolaorsini.altervista.org, Karolinska Institutet,
        Sweden
    nicola.orsini@imm.ki.se

Also see

    [R] destring
    [U] Commands for dealing with strings

On-line:  help for destring, macro, strfun