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  • Specification of funnel plot with -funnelcompar-

    Hi Statalisters

    I want to assess county differences in medication rates in Norway to detect outliers. For this purpose I want to use funnel plots as recommended by Spiegelhalter (see e.g. The Art of Statistics). I am trying this on publically available Norwegian data. However, I have worked on this for some time now and I am not sure whether I am specifying the funnel plot correctly, and I wonder if any of you have some input on this.

    Specifically, I am having some trouble with (i) specifying the correct weights (the plot command only works with the -nowei- option), and (ii) the confidence intervals seem to narrow, although I suspect this may be due to sample size, not my specification of the funnel plot.

    It's county data for a year so it's a small sample with 18 observations. The medication rate is by 1000 individuals per county. I've gathered population data per county, and made a population rate in 1000's so it's scaled to the medication rate.

    I obtain the standard deviation of the medication rate by
    Code:
     egen sd_medrate=sd(medrate1000)
    The funnel plot command is then:
    Code:
    funnelcompar medrate1000 poprate1000 county sd_medrate, cont nowei
    Which gives:
    Click image for larger version

Name:	funnelplot_nowei.png
Views:	2
Size:	50.7 KB
ID:	1518346


    Without -nowei- I get the following error message:
    Code:
    may not use noninteger frequency weights
    As it's such a small sample, I'll include the total dataset in dataex:
    Code:
    * Example generated by -dataex-. To install: ssc install dataex
    clear
    input long county float(county_pop medrate1000 poprate1000 sd_medrate)
     4  72856 6.37  72.856 1.6318192
    12 107080 4.68  107.08 1.6318192
     2 108499 9.68 108.499 1.6318192
    14 156494 4.76 156.494 1.6318192
    13 168231 7.46 168.231 1.6318192
    16 170377  6.4 170.377 1.6318192
     9 185216 5.56 185.216 1.6318192
     5 190709 8.24 190.709 1.6318192
    17 231286 7.83 231.286 1.6318192
     8 236271 9.19 236.271 1.6318192
     7 251262 5.87 251.262 1.6318192
     3 257673 6.28 257.673 1.6318192
    18 271662 7.59 271.662 1.6318192
    15 422102 5.61 422.102 1.6318192
    11 427947 6.51 427.947 1.6318192
     6 477175 4.79 477.175 1.6318192
     1 536499 5.32 536.499 1.6318192
    10 586860 3.62  586.86 1.6318192
    end
    label values county fylke
    label def fylke 1 "Akershus", modify
    label def fylke 2 "Aust-Agder", modify
    label def fylke 3 "Buskerud", modify
    label def fylke 4 "Finnmark", modify
    label def fylke 5 "Hedmark", modify
    label def fylke 6 "Hordaland", modify
    label def fylke 7 "Møre og Romsdal", modify
    label def fylke 8 "Nordland", modify
    label def fylke 9 "Oppland", modify
    label def fylke 10 "Oslo", modify
    label def fylke 11 "Rogaland", modify
    label def fylke 12 "Sogn og Fjordane", modify
    label def fylke 13 "Telemark", modify
    label def fylke 14 "Troms", modify
    label def fylke 15 "Trøndelag", modify
    label def fylke 16 "Vest-Agder", modify
    label def fylke 17 "Vestfold", modify
    label def fylke 18 "Østfold", modify
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