Last updated: 2020-12-17

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Knit directory: 2020_cts_bn/

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Rmd e196111 bernard-liew 2020-12-16 augmented reporting
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Rmd fe17d91 bernard-liew 2020-10-26 initial analysis

Load package

if (!require("pacman")) install.packages("pacman")
Loading required package: pacman
Warning: package 'pacman' was built under R version 3.6.1
pacman::p_load(tidyverse,
               qgraph,
               stats,
               bootnet,
               igraph,
               arsenal,
               flextable,
               officer,
               cowplot,
               huge)

Import data

if (file.exists("output/network_res.RDS")) {
  
  dat2 <- readRDS("output/network_res.RDS")
  
  list2env(dat2 ,.GlobalEnv)
  
  skip_eval <- TRUE

  } else {
  
  dat <- readRDS ("output/dat.RDS")
  
  skip_eval <- FALSE
  }

# Helper for nice descriptive table

meanNsd_transform <- function (x) {

  m <- round (x[[1]][1], 2)
  s <- round (x[[1]][2], 2)

  m_s <- paste0(m, "(", s, ")")

  return (m_s)
}

Clean data

if (skip_eval == FALSE) {
  
  dat_base <- dat[, !grepl ("naff.*base", names (dat))] 
  dat_base <- dat_base[, grepl ("aff|base", names (dat_base))] 
  dat_base <- dat_base %>%
    select (-worst_pain_base, - aff_side) %>%
    rename (func = cts_func_base,
            severity = cts_severe_base) 
  names (dat_base) <- str_remove_all (names(dat_base), "_base|mean_|_aff")
  
  node_labs <- names(dat_base)
  
  names(dat_base) <- paste0("V", 1:ncol(dat_base))
  
  dat_base %>%
    pivot_longer(cols = everything (),
                 names_to = "var",
                 values_to = "val") %>%
    ggplot () +
    geom_histogram (aes (val)) +
    facet_wrap (~ var, ncol = 5, scales = "free_x")
  
}

Descriptive summary

dat_sub <- dat %>%
  dplyr::select (age, 
                 pain_years, 
                 mean_pain_base,
                 ppt_medn_aff_base, 
                 ppt_uln_aff_base,
                 ppt_radn_aff_base,
                 ppt_neck_aff_base,
                 ppt_cts_aff_base,
                 ppt_ta_aff_base,
                 cts_func_base,
                 cts_severe_base,
                 dep_base)

names (dat_sub) <- str_remove_all (names(dat_sub), "_base|mean_|_aff")

tab1 <- tableby ( ~. , data = dat_sub, digits = 2, digits.p = 2) 

summary (tab1)
Overall (N=105)
age
   Mean (SD) 46.82 (9.17)
   Range 21.00 - 64.00
pain_years
   Mean (SD) 3.24 (2.91)
   Range 0.50 - 18.00
pain
   Mean (SD) 5.02 (1.75)
   Range 0.00 - 8.00
ppt_medn
   Mean (SD) 194.32 (54.39)
   Range 82.00 - 333.00
ppt_uln
   Mean (SD) 299.30 (80.82)
   Range 93.00 - 498.00
ppt_radn
   Mean (SD) 226.43 (64.02)
   Range 89.00 - 458.00
ppt_neck
   Mean (SD) 172.20 (48.47)
   Range 63.00 - 307.00
ppt_cts
   Mean (SD) 352.77 (113.98)
   Range 127.00 - 652.00
ppt_ta
   Mean (SD) 325.20 (88.15)
   Range 101.00 - 544.00
cts_func
   Mean (SD) 2.35 (0.57)
   Range 1.12 - 4.25
cts_severe
   Mean (SD) 2.63 (0.66)
   Range 1.27 - 5.00
dep
   Mean (SD) 3.84 (2.37)
   Range 0.00 - 9.00

Network analysis

On baseline data

if (skip_eval == FALSE) {
  
  df <- dat_base
  df <- huge.npn (df)

  set.seed (1)
  nw <- estimateNetwork(df, 
                      default="EBICglasso",
                      corMethod = "cor",
                      tuning = 0.5,
                      lambda.min.ratio = 0.001,
                      corArgs =
                        list(method = "pearson",
                             use = "pairwise.complete.obs"))
  
}

Plot network

Arcs in blue means a positive correlation between connecting variables.

Arcs in red means a netative correlation between connecting variables.

Thickness of arcs gives you a qualitative indication of correlation magnitude.

nw_plot <- plot (nw, nodeNames = node_labs,  layout = "spring", legend = TRUE)

wts_df <- nw_plot$Edgelist %>%
  bind_cols() %>%
  select (from, to, weight) %>%
  mutate_all (round, 2)

wts_df %>% 
  mutate (weight_abs = abs (weight)) %>%
  slice_max (weight_abs, n = 10)
# A tibble: 10 x 4
    from    to weight weight_abs
   <dbl> <dbl>  <dbl>      <dbl>
 1     2     4  0.34       0.34 
 2     8    10  0.3        0.3  
 3     6     7  0.290      0.290
 4     8     9  0.25       0.25 
 5     3     7  0.24       0.24 
 6     5     7  0.23       0.23 
 7     2     6  0.2        0.2  
 8     1     9  0.2        0.2  
 9     4     5  0.19       0.19 
10     2     3  0.18       0.18 

Centrality

High centrality nodes have strong connections to many other nodes, and act as hubs that connect otherwise disparate nodes to one another.

Low centrality nodes exist on the periphery of the network, with fewer and weaker connections to other nodes of the network.

Strength is the sum of the absolute value of its connections with other nodes in the network.

Closeness centrality is defined as the inverse of the sum of the distances of the focal node from all the other nodes in the network. Closeness is the average shortest path between a given node and the remaining nodes in the network. Nodes with higher closeness are more proximally connected to the rest of the network.

Betweenness is the number of times in which a given node lies on the shortest path between two other nodes.

The greater the value of centrality indices to one, the more important the variable.

centr <- centralityPlot(nw,  
                        include = c("Strength", "Closeness", "Betweenness"), 
                        scale = "relative", 
                        labels = node_labs)
Note: relative centrality indices are shown on x-axis rather than raw centrality indices.

Accuracy

Edge weights stability

if (skip_eval == FALSE) {
  edge_wts <- bootnet(nw,
                    nBoots = 2000,
                    nCores = 6,
                    statistics = "edge")
 
}

plot (edge_wts, satistics = "edge", plot = "area", order = "sample", CIstyle = "SE")

Centrality stability

if (skip_eval == FALSE) {
  stats2boot <- c("edge", "strength", "expectedInfluence", "closeness", "betweenness")
  centr_stb <- bootnet(nw,
                       nBoots = 2000,
                       nCores = 6,
                       statistics = stats2boot,
                       type = "case")
  
  cor_stb <-  corStability (centr_stb)

}

plot (centr_stb, statistics = c("strength", "closeness", "betweenness"))

Save data

dat2save <- list ("dat" = dat,
                  "df" = df,
                  "nw" = nw,
                  "nw_plot" = nw_plot,
                  "centr" = centr,
                  "centr_stb" = centr_stb,
                  "edge_wts" = edge_wts,
                  "cor_stb" = cor_stb,
                  "node_labs" = node_labs,
                  "stats2boot" = stats2boot,
                  "Sim" = Sim)

saveRDS(dat2save,
        "output/network_res.RDS")

sessionInfo()
R version 3.6.0 (2019-04-26)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18363)

Matrix products: default

locale:
[1] LC_COLLATE=English_United Kingdom.1252 
[2] LC_CTYPE=English_United Kingdom.1252   
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] huge_1.3.4.1     cowplot_1.1.0    officer_0.3.15   flextable_0.5.11
 [5] arsenal_3.5.0    igraph_1.2.6     bootnet_1.4.3    qgraph_1.6.5    
 [9] forcats_0.5.0    stringr_1.4.0    dplyr_1.0.2      purrr_0.3.4     
[13] readr_1.4.0      tidyr_1.1.2      tibble_3.0.4     ggplot2_3.3.2   
[17] tidyverse_1.3.0  pacman_0.5.1    

loaded via a namespace (and not attached):
  [1] utf8_1.1.4           R.utils_2.10.1       tidyselect_1.1.0    
  [4] htmlwidgets_1.5.2    grid_3.6.0           munsell_0.5.0       
  [7] codetools_0.2-18     withr_2.3.0          colorspace_2.0-0    
 [10] NetworkToolbox_1.4.0 highr_0.8            knitr_1.30          
 [13] uuid_0.1-4           rstudioapi_0.13      stats4_3.6.0        
 [16] labeling_0.4.2       git2r_0.27.1         mnormt_2.0.2        
 [19] farver_2.0.3         rprojroot_2.0.2      vctrs_0.3.5         
 [22] generics_0.1.0       xfun_0.19            R6_2.5.0            
 [25] doParallel_1.0.16    smacof_2.1-1         assertthat_0.2.1    
 [28] promises_1.1.1       scales_1.1.1         nnet_7.3-14         
 [31] gtable_0.3.0         weights_1.0.1        workflowr_1.6.2     
 [34] rlang_0.4.8          systemfonts_0.3.2    splines_3.6.0       
 [37] wordcloud_2.6        broom_0.7.2          checkmate_2.0.0     
 [40] yaml_2.2.1           reshape2_1.4.4       abind_1.4-5         
 [43] modelr_0.1.8         d3Network_0.5.2.1    backports_1.2.0     
 [46] httpuv_1.5.4         Hmisc_4.4-1          tools_3.6.0         
 [49] psych_2.0.9          lavaan_0.6-7         ellipsis_0.3.1      
 [52] RColorBrewer_1.1-2   polynom_1.4-0        Rcpp_1.0.5          
 [55] plyr_1.8.6           base64enc_0.1-3      rpart_4.1-15        
 [58] pbapply_1.4-3        haven_2.3.1          cluster_2.1.0       
 [61] fs_1.5.0             survey_4.0           magrittr_2.0.1      
 [64] data.table_1.13.2    openxlsx_4.2.3       reprex_0.3.0        
 [67] tmvnsim_1.0-2        mvtnorm_1.1-1        matrixcalc_1.0-3    
 [70] whisker_0.4          hms_0.5.3            evaluate_0.14       
 [73] rio_0.5.16           jpeg_0.1-8.1         readxl_1.3.1        
 [76] gridExtra_2.3        shape_1.4.5          compiler_3.6.0      
 [79] ellipse_0.4.2        mice_3.12.0          crayon_1.3.4        
 [82] R.oo_1.24.0          htmltools_0.5.0      corpcor_1.6.9       
 [85] later_1.1.0.1        Formula_1.2-4        lubridate_1.7.9.2   
 [88] DBI_1.1.0            relaimpo_2.2-3       mgm_1.2-10          
 [91] dbplyr_2.0.0         MASS_7.3-53          boot_1.3-25         
 [94] IsingSampler_0.2.1   Matrix_1.2-18        IsingFit_0.3.1      
 [97] car_3.0-10           cli_2.2.0            heplots_1.3-7       
[100] mitools_2.4          R.methodsS3_1.8.1    gdata_2.18.0        
[103] parallel_3.6.0       BDgraph_2.63         pkgconfig_2.0.3     
[106] foreign_0.8-71       xml2_1.3.2           foreach_1.5.1       
[109] pbivnorm_0.6.0       rvest_0.3.6          digest_0.6.27       
[112] rmarkdown_2.5        cellranger_1.1.0     htmlTable_2.1.0     
[115] gdtools_0.2.2        curl_4.3             gtools_3.8.2        
[118] rjson_0.2.20         lifecycle_0.2.0      nlme_3.1-150        
[121] glasso_1.11          jsonlite_1.7.1       carData_3.0-4       
[124] fansi_0.4.1          pillar_1.4.7         lattice_0.20-41     
[127] httr_1.4.2           plotrix_3.7-8        survival_3.2-7      
[130] glue_1.4.2           networktools_1.2.3   zip_2.1.1           
[133] fdrtool_1.2.15       png_0.1-7            iterators_1.0.13    
[136] candisc_0.8-3        glmnet_4.0-2         class_7.3-17        
[139] stringi_1.4.6        nnls_1.4             latticeExtra_0.6-29 
[142] eigenmodel_1.11      e1071_1.7-4