This data set gives the observed number of bolls produced by the cotton plants at five growth stages: vegetative, flower-bud, blossom, fig and cotton boll; to examine the effect of five defoliation levels (0\
data(cottonbolls)A data frame with 125 observations on 4 variables.
number of bolls produced by two cotton plants at harvest
growth stage
artificial defoliation level
square of def
Supplementary Content of Zeviani et al. (2014): http://www.leg.ufpr.br/doku.php/publications:papercompanions:zeviani-jas2014
Zeviani, W.M., Riberio P.J. Jr., Bonat, W.H., Shimakura S.E. and Muniz J.A. (2014). The Gamma-count distribution in the analysis of experimental underdispersed data. Journal of Applied Statistics 41, 2616--26.
### Huang (2017) Page 373--375: Underdispersed Cotton bolls data
### Model fitting for predictor V
data(cottonbolls)
M.bolls <- glm.cmp(nc ~ 1 + stages:def + stages:def2, data = cottonbolls)
M.bolls
#>
#> Call: glm.cmp(formula = nc ~ 1 + stages:def + stages:def2, data = cottonbolls)
#>
#> Linear Model Coefficients:
#> (Intercept) stagesvegetative:def stagesflower bud:def
#> 2.1896000 0.4368500 0.2897100
#> stagesblossom:def stagesfig:def stagescotton boll:def
#> -1.2425000 0.3648200 0.0089438
#> stagesvegetative:def2 stagesflower bud:def2 stagesblossom:def2
#> -0.8052100 -0.4878400 0.6728600
#> stagesfig:def2 stagescotton boll:def2
#> -1.3103000 -0.0199660
#>
#> Dispersion (nu): 4.85
#> Degrees of Freedom: 124 Total (i.e. Null); 114 Residual
#> Null Deviance: 345.9363
#> Residual Deviance:
#> AIC: 440.8229
#>
summary(M.bolls)
#>
#> Call: glm.cmp(formula = nc ~ 1 + stages:def + stages:def2, data = cottonbolls)
#>
#> Deviance Residuals:
#> Min 1Q Median 3Q Max
#> -2.29766 -0.68297 -0.04972 0.74987 2.74460
#>
#> Linear Model Coefficients:
#> Estimate Std.Err Z value Pr(>|z|)
#> (Intercept) 2.189562 0.029407 74.456 < 2e-16 ***
#> stagesvegetative:def 0.436854 0.239663 1.823 0.06834 .
#> stagesflower bud:def 0.289708 0.235822 1.229 0.21926
#> stagesblossom:def -1.242507 0.283166 -4.388 1.14e-05 ***
#> stagesfig:def 0.364816 0.264720 1.378 0.16817
#> stagescotton boll:def 0.008944 0.233866 0.038 0.96949
#> stagesvegetative:def2 -0.805212 0.271949 -2.961 0.00307 **
#> stagesflower bud:def2 -0.487844 0.263290 -1.853 0.06390 .
#> stagesblossom:def2 0.672864 0.319551 2.106 0.03523 *
#> stagesfig:def2 -1.310267 0.316982 -4.134 3.57e-05 ***
#> stagescotton boll:def2 -0.019966 0.256498 -0.078 0.93795
#> ---
#> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
#>
#> (Dispersion parameter for Mean-CMP estimated to be 4.852)
#>
#>
#> Null deviance: 345.94 on 124 degrees of freedom
#> Residual deviance: 125.26 on 114 degrees of freedom
#>
#> AIC: 440.8229
#>