gambia                 package:geoR                 R Documentation

_G_a_m_b_i_a _M_a_l_a_r_i_a _D_a_t_a

_D_e_s_c_r_i_p_t_i_o_n:

     Malaria prevalence in children recorded at villages in The Gambia,
     Africa.

_U_s_a_g_e:

     data(gambia)

_F_o_r_m_a_t:

     Two objects are made available: \begin{enumerate}

     *  'gambia'
         A data frame with 2035 observations on the following 8
        variables.

     _x x-coordinate of the village (UTM).  

     _y y-coordinate of the village (UTM).  

     _p_o_s presence (1) or absence (0) of malaria in a blood sample taken
          from the child.

     _a_g_e age of the child, in days

     _n_e_t_u_s_e indicator variable denoting whether (1) or not (0) the
          child regularly sleeps under a bed-net.  

     _t_r_e_a_t_e_d indicator variable denoting whether (1) or not (0) the
          bed-net is treated (coded 0 if netuse=0).

     _g_r_e_e_n satellite-derived measure of the green-ness of vegetation in
          the immediate vicinity of the village (arbitrary units).  

     _p_h_c indicator variable denoting the presence (1) or absence (0) of
          a health center in the village.  

     *  'gambia.borders'
         A data frame with 2 variables:

     _x x-coordinate of the country borders.  

     _y y-coordinate of the country borders.  

     \end{enumerate}

_R_e_f_e_r_e_n_c_e_s:

     Thomson, M., Connor, S., D Alessandro, U., Rowlingson, B., Diggle,
     P., Cresswell, M. & Greenwood, B. (1999). Predicting malaria
     infection in Gambian children from satellite data and bednet use
     surveys: the importance of spatial correlation in the
     interpretation of results. _American Journal of Tropical Medicine
     and Hygiene_ 61: 2-8.

     Diggle, P., Moyeed, R., Rowlingson, B. & Thomson, M. (2002).
     Childhood malaria in The Gambia: a case-study in model-based
     geostatistics, _Applied Statistics_.

_E_x_a_m_p_l_e_s:

     plot(gambia.borders, type="l", asp=1)
     points(gambia[,1:2], pch=19)
     # a built-in function for a zoomed map
     gambia.map()
     # Building a "village-level" data frame
     ind <- paste("x",gambia[,1], "y", gambia[,2], sep="")
     village <- gambia[!duplicated(ind),c(1:2,7:8)]
     village$prev <- as.vector(tapply(gambia$pos, ind, mean))
     plot(village$green, village$prev)

