fconc<-c(31.0,14.5,11.8,11.2,7.5,3.9,3.3,1.4,.8)
  ndead<-c(60,60,46,47,10,1,0,2,1)

  nrisk<-rep(60,length(ndead))
  fluor.df<-data.frame(conc=fconc,ndead=ndead,nrisk=nrisk)

  fluor.fit<-glm(cbind(ndead,nrisk-ndead)~conc,
                  family=binomial(link=logit),
                  data=fluor.df)

  summary(fluor.fit)


  Coefficients:
                   Value Std. Error   t value
  (Intercept) -6.2811969 0.61266037 -10.25233
         conc  0.6585055 0.05964345  11.04070

      Null Deviance: 514.9841 on 8 degrees of freedom

  Residual Deviance: 14.69952 on 7 degrees of freedom

  Correlation of Coefficients:
       (Intercept)
  conc -0.9612874