[R] gamma distribution don't allow negative value in GLMs?

chao gai chaogai at duineveld.demon.nl
Sun Oct 15 14:23:59 CEST 2006


I think the 0 values for snail are hurting you.

Kees

On Sunday 15 October 2006 13:10, zhijie zhang wrote:
> Dear friends,
>  when i use glm() to fit my data,  i use
> glm(formula = snail ~ vegtype + mhveg + humidity + elevation + soiltem,
> *family = Gamma(link = inverse),* data =a,))
> It shows:  error in eval(expr, envir, enclos) : *gamma distribution don't
> allow negative value*.
>
> But i use
> result<-glm(formula = snail ~ vegtype + mhveg + humidity + elevation +
> soiltem, family = poisson, data =a) #this works
>  In fact , there isn't any negative value in my dataset, who can tell me
> the reason?
> Thanks very much!
>  I copy my data here so you can check it:
>       vegtype mhveg humidity soiltem elevation snail
> 1         diluo  35.0 0.279851    21.1       low   162
> 2         diluo  25.0 0.316092    23.1       low   113
> 3         yuhao  35.0 0.297238    21.7       low   105
> 4   huanghuacai   1.5 0.310687    23.1       low     5
> 5   huanghuacai   2.0 0.267868    28.3       low     1
> 6         yuhao  25.0 0.290135    21.9       low    10
> 7   huanghuacai   1.0 0.285207    27.7       low     6
> 8   huanghuacai   2.0 0.252973    28.3       low     1
> 9   huanghuacai   1.5 0.270000    28.1       low     1
> 10  huanghuacai   2.5 0.300000    29.1       low     1
> 11  huanghuacai   2.0 0.296154    29.1       low     0
> 12  huanghuacai   2.0 0.302874    27.5       low     3
> 13  huanghuacai   1.5 0.301499    28.9       low     0
> 14  huanghuacai   3.0 0.291513    30.3       low     1
> 15  huanghuacai   1.0 0.273438    31.1       low     3
> 16  huanghuacai   1.5 0.290116    27.9       low    19
> 17  huanghuacai   2.5 0.198932    31.9       low     0
> 18  huanghuacai   2.0 0.390000    30.5      high     4
> 19  huanghuacai   2.5 0.282595    30.7      high     0
> 20  huanghuacai   1.0 0.266097    24.7      high    14
> 21        yuhao  30.0 0.240516    26.9      high    51
> 22        yuhao  35.0 0.227541    26.7      high    84
> 23        yuhao  20.0 0.252833    28.3       low    30
> 24        diluo  40.0 0.303030    27.9       low    91
> 25        hucao  80.0 0.303867    24.5       low   114
> 26        diluo  25.0 0.334948    26.7       low   115
> 27        hucao  60.0 0.306897    26.5       low    23
> 28        hucao  75.0 0.314465    25.7       low    43
> 29        yuhao  30.0 0.251783    26.1       low    77
> 30        diluo  10.0 0.277778    26.1       low    62
> 31        yuhao  25.0 0.291716    26.1       low    78
> 32        hucao  90.0 0.288800    24.5       low    35
> 33        diluo  25.0 0.337830    26.3      high    75
> 34        yuhao  13.0 0.296599    27.7      high    23
> 35        hucao  70.0 0.279498    26.3      high   116
> 36        diluo   3.0 0.281481    28.1      high    25
> 37        hucao  70.0 0.296000    23.7      high    83
> 38        diluo  10.0 0.272662    27.7       low    56
> 39        hucao  70.0 0.289796    25.3      high   112
> 40        diluo   5.0 0.339716    27.9      high    84
> 41        yuhao  35.0 0.231427    24.9      high    88
> 42        hucao  80.0 0.273810    24.1      high   134
> 43        yuhao  40.0 0.272789    25.1      high    53
> 44        yuhao  45.0 0.226036    25.1      high    88
> 45        yuhao  55.0 0.285495    23.9      high    76
> 46        hucao  80.0 0.252185    23.9      high   106
> 47        diluo  15.0 0.289933    24.5      high   194
> 48        hucao  95.0 0.261756    23.1      high    35
> 49        hucao  55.0 0.239819    24.7      high    21
> 50        hucao  75.0 0.254307    23.9      high    41
> 51  huanghuacai   1.0 0.286432    23.7       low    18
> 52  huanghuacai   2.0 0.301342    23.1       low     2
> 53  huanghuacai   2.0 0.369565    23.3       low     5
> 54  huanghuacai   1.5 0.245833    24.3       low     4
> 55  huanghuacai   1.0 0.315679    24.1       low     4
> 56  huanghuacai   2.5 0.296124    23.7       low     4
> 57  huanghuacai   2.0 0.312667    25.7       low     3
> 58  huanghuacai   3.0 0.300870    25.7       low     0
> 59  huanghuacai   2.0 0.303743    26.5       low     2
> 60  huanghuacai   1.0 0.269799    25.3       low     7
> 61        hucao  75.0 0.281250    22.5       low    14
> 62        yuhao  35.0 0.350350    23.3       low    63
> 63        hucao  65.0 0.304545    22.7       low    17
> 64        diluo   7.0 0.310056    24.9       low    45
> 65        hucao  80.0 0.288000    22.9       low    27
> 66        hucao  80.0 0.284211    22.7       low    46
> 67        diluo  25.0 0.281379    23.5       low   161
> 68        hucao  80.0 0.290533    23.3       low   117
> 69        yuhao  27.0 0.316568    24.1       low   106
> 70        yuhao  28.0 0.285156    25.1       low    82
> 71        yuhao  30.0 0.266667    24.5       low    55
> 72        hucao  85.0 0.290345    23.9       low    54
> 73        yuhao  35.0 0.315789    24.1       low    81
> 74        diluo  15.0 0.286598    28.3       low   102
> 75        yuhao  45.0 0.314211    24.1       low    85
> 76        yuhao  25.0 0.268794    25.1       low    63
> 77        hucao  80.0 0.275691    23.9       low    59
> 78        hucao 100.0 0.316614    24.1       low    46
> 79        yuhao  40.0 0.336683    25.5       low    70
> 80        diluo  20.0 0.270874    26.1      high   167
> 81        yuhao  50.0 0.271483    24.3      high   125
> 82        hucao  80.0 0.238095    25.1      high   200
> 83        yuhao  30.0 0.241202    26.7       low   122
> 85        diluo  35.0 0.244531    28.1      high   186
> 86        yuhao  55.0 0.274038    24.9       low   208
> 87        hucao  80.0 0.303488    25.7       low    87
> 88        hucao  85.0 0.278846    25.3       low    25
> 89        diluo   5.0 0.270330    28.3      high    18
> 90        yuhao  35.0 0.296296    24.7      high    21
> 91        diluo   1.0 0.274306    27.9       low    23
> 92        diluo   3.0 0.262673    29.5       low     0
> 93        diluo   8.0 0.268750    27.7      high    21
> 94        hucao  70.0 0.265734    26.1      high     2
> 95        hucao  85.0 0.275373    24.3       low     6
> 96        diluo  10.0 0.284091    27.1       low     2
> 97        hucao  85.0 0.268229    25.3       low     0
> 98        hucao  90.0 0.293056    23.9       low     0
> 99        yuhao  35.0 0.277483    24.7       low     3
> 100       hucao  95.0 0.286822    24.3      high     1
> 101       hucao  88.0 0.285946    23.9      high     5
> 102       yuhao  35.0 0.268313    24.5       low     1
> 103       yuhao  25.0 0.285714    24.3      high     0
> 104       yuhao  25.0 0.294675    24.5      high     2
> 105       yuhao  38.0 0.275385    23.5      high     6
> 106       hucao  92.0 0.302415    23.3       low    15
> 107       hucao  83.0 0.276190    23.9       low     5
> 108       yuhao  55.0 0.285068    24.1       low    20
> 109       hucao  80.0 0.276552    23.5       low     5
> 110       hucao  95.0 0.281818    23.9       low     0
> 111       hucao 105.0 0.270293    23.1       low    13
> 112       hucao  95.0 0.291209    20.1       low    23
> 113       hucao  90.0 0.273196    20.9       low    48
> 114       yuhao  27.0 0.261986    20.5       low    49
> 115       yuhao  40.0 0.265187    20.5       low     9
> 116       yuhao  27.0 0.307143    20.9       low    27
> 117       yuhao  33.0 0.293194    20.7       low    34
> 118       yuhao  25.0 0.211399    20.9       low    38
> 119       yuhao  20.0 0.277372    21.7       low    30
> 120       hucao  95.0 0.346224    20.5       low    88
> 121       hucao  90.0 0.330380    21.3       low    91
> 122       yuhao  23.0 0.337884    23.3       low    70
> 123       hucao  80.0 0.322488    22.3       low   103
> 124       hucao  80.0 0.300000    22.1       low    51
> 125       hucao 100.0 0.326241    21.7       low    82
> 126       hucao  95.0 0.298571    21.9       low   104
> 127       hucao  95.0 0.296029    21.7       low    39
> 128       hucao  85.0 0.260082    21.7       low    73
> 129       hucao  93.0 0.304167    21.9       low   103
> 130       hucao  90.0 0.289941    22.3       low    65
> 131       hucao  85.0 0.339189    22.7       low   112
> 132       yuhao  30.0 0.314103    23.3       low    32
> 133       yuhao  28.0 0.293464    23.5       low    29
> 134       yuhao  45.0 0.310256    23.3       low    92
> 135       yuhao  42.0 0.375573    23.1       low    49
> 136       hucao  90.0 0.313846    23.1       low    47
> 137       yuhao  25.0 0.303601    23.9       low    54
> 138       hucao  85.0 0.339394    23.3       low    64
> 139       hucao  90.0 0.285934    23.1       low    68
> 140       yuhao  27.0 0.327915    23.9       low    62
> 141       hucao  85.0 0.372679    23.9       low    94
> 142       hucao  85.0 0.350147    22.5       low   174
> 143       yuhao  35.0 0.278014    23.7       low    38
> 144       hucao 100.0 0.327273    22.9       low   105
> 145       hucao  68.0 0.309286    24.9       low   105
> 146       hucao  85.0 0.279503    24.3      high    60
> 147       hucao  95.0 0.310870    23.3      high    42
> 148       hucao  95.0 0.309353    24.3      high    64
> 149       hucao  92.0 0.280745    23.5       low    37
> 150       yuhao  25.0 0.300355    24.3      high   107
> 151       yuhao  40.0 0.307692    24.7      high    86
> 152       hucao  40.0 0.273292    25.3      high    72
> 153       hucao  53.0 0.305096    24.7      high   109
> 154       hucao  50.0 0.306288    24.7      high    76
> 155       hucao  95.0 0.312268    22.3       low    60
> 156       hucao  90.0 0.301170    22.7       low    62
> 157       yuhao  38.0 0.305109    22.9       low    68
> 158       hucao  25.0 0.300719    25.3       low    21
> 159       hucao  80.0 0.252149    23.1       low    50
> 160       hucao  90.0 0.290306    23.3       low    63
> 161       hucao  33.0 0.293772    25.1       low    63



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