diff --git a/README.md b/README.md
index 4ef9dd1..857797c 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,31 @@
 # Virtual Surrounding Impression analysis
 
-Version: 0.1b
+The tool for checking Virtual Surrounding Impression.  
+  
+It does the following two detections on the dataset:
+- interviews that were _most likely_ taken at the same location by the same interviewer (read: faking at home)
+- individual interviews that were _most likely_ conducted at multiple locations (multiple sittings or faking at multiple places)  
+  
+Please use the tool as an *additional* and not _sole_ indicator of undesired interviewer behaviour.  
+  
+Also, remember the tool is based on WIFI data.  
+Cases, conducted while the WIFI is turned off (or no wifi access points are visible) *will have the same VSI* and will appear to be taken at the same location.
+
+  
+Support: myESS or [mailto: may.dousak@fdv.uni-lj.si]
 
 ## Changelog
 
+*1.0 R 230117 - 17th Jan 2023*
+- cleaned up the code
+- created common files that can be shared with the other tools
+- script now checks the data and reports on the errors before processing
+- user friendly error messages and instructions provided when errors are detected
+
+
+*1.0b - 16th Jan 2023*
+R markdown version, knits PDF report
+
 *0.1b - 13th Jan 2023*  
 
 First working R version, translated from Python.  
diff --git a/components/VSI.R b/components/VSI.R
index 59fd837..28a4f3e 100644
--- a/components/VSI.R
+++ b/components/VSI.R
@@ -1,22 +1,28 @@
-# checks the data, returns FALSE in case something is not OK
-check_data <- function (dataset) {
-  if (!is.null(dataset$VSI1) && !is.null(dataset$VSI2) && !is.null(dataset$VSI3) && !is.null(dataset$idno)) {
-    cat ("All the required variables are present, continuing with the analysis.  ")
-    
+# checks the main data, returns FALSE in case something is not OK
+# for VSI, we need at least: idno, cntry, VSI1, VSI2, VSI3
+
+check_main_file <- function (dataset) {
+
+  if (!is.null(dataset$VSI1) && !is.null(dataset$VSI2) && !is.null(dataset$VSI3) 
+      && !is.null(dataset$idno)  && !is.null(dataset$cntry)) {
+
     return (TRUE)
     
   } else {
     if (is.null(dataset$VSI1)) {
-      cat ("VSI1 variable is missing in the dataset.  ");
+      cat ("VSI1 variable is missing in the main dataset.  ");
     }
     if (is.null(dataset$VSI2)) {
-      cat ("VSI2 variable is missing in the dataset.  ");
+      cat ("VSI2 variable is missing in the main dataset.  ");
     }
     if (is.null(dataset$VSI3)) {
-      cat ("VSI3 variable is missing in the dataset.  ");
+      cat ("VSI3 variable is missing in the main dataset.  ");
     }
     if (is.null(dataset$idno)) {
-      cat ("idno variable (interview ID) is missing in the dataset.  ");
+      cat ("idno variable (interview ID) is missing in the main dataset.  ");
+    }
+    if (is.null(dataset$cntry)) {
+      cat ("cntry variable (country code) is missing in the main dataset.  ");
     }
     
     cat ("**Please check your dataset and try again**")
@@ -24,6 +30,29 @@ check_data <- function (dataset) {
   }  
 }
 
+# checks the intervier data, returns FALSE in case something is not OK
+# here, we need at least: idno, cntry, intnum
+check_inwer_file <- function (dataset) {
+  
+  if (!is.null(dataset$cntry) && !is.null(dataset$idno) && !is.null(dataset$intnum)) {
+    
+    return (TRUE)
+    
+  } else {
+    if (is.null(dataset$intnum)) {
+      cat ("intnum (intervie**wer** ID variable is missing in the interviewer dataset.  ");
+    }
+    if (is.null(dataset$idno)) {
+      cat ("idno variable (interview ID) is missing in the interviewer dataset.  ");
+    }
+    if (is.null(dataset$cntry)) {
+      cat ("cntry variable (country code) is missing in the interviewer dataset.  ");
+    }    
+    cat ("**Please check your dataset and try again**")
+    return (FALSE)
+  }  
+}
+
 
 
 # Extracts access points fingerprints from the data (5 APs from 1 VSI)
diff --git a/components/common.R b/components/common.R
new file mode 100644
index 0000000..bc2ddfa
--- /dev/null
+++ b/components/common.R
@@ -0,0 +1,91 @@
+# call this at the top of the Rmd
+common_defs <- function () {
+  knitr::opts_chunk$set(echo = TRUE, results = "hide", message = TRUE, dev = "cairo_pdf", warning = TRUE)
+  knitr::opts_chunk$set(fig.pos = 'H')
+  
+  options(knitr.table.format = "latex", knitr.kable.NA = "")
+  
+  Sys.setlocale("LC_ALL","English")
+}
+
+# checks if file names are provided and file paths are valid.
+# returns TRUE if everything's OK or FALSE if not.
+
+check_files <- function (main, inwer) {
+  
+  pass = TRUE
+  
+  if (is.null(main) || main == "") {
+    
+    pass = FALSE
+    cat ("**Main data file not provided. Please profile main data file path as 'mainFile' parameter to the script!**  \n")
+  }
+  
+  if (is.null(inwer) || inwer == "") {
+    
+    pass = FALSE
+    cat ("**Interviewer data file not provided. Please profile interviewer data file path as 'intFile' parameter to the script!**  \n")
+  }
+  
+  
+  if (!file.exists(main)) {
+    
+    pass= FALSE
+    cat (paste("**I can't open the main data file '", main, "'.**  \n  
+      Did you provide a valid path to the file?  \n  
+      Please make sure that:  
+       - it is stored on a local (not network) drive
+       - file name or file path does not contain any non-english characters
+       - file name and file path only contains characters (a-z), numbers (0-1), dash (-) or underline (_)"))
+  }
+  
+  if (!file.exists(inwer)) {
+    cat (paste("**I can't open the interviewer data file '", inwer, "'.**  \n  
+      Did you provide a valid path to the file?  \n  
+      Please make sure that:  
+       - it is stored on a local (not network) drive
+       - file name or file path does not contain any non-english characters
+       - file name and file path only contains characters (a-z), numbers (0-1), dash (-) or underline (_)"))
+  }
+  
+  return (pass)
+}
+
+# loads the files and returns merged data
+# also checks if the needed variables are present
+# (check_data must be provided in additional R file, as it differs between tests)
+
+load_files <- function (main, inwer) {
+  
+  pass = TRUE
+  
+  # main file
+  dataset <- read.csv2(main, dec=".", stringsAsFactors=F)
+  # exit if data is not OK
+  
+  if (check_main_file(dataset) == FALSE) {
+    pass = FALSE
+  }  
+  
+  #interviewer file
+  Inwer <- read.csv2(inwer, dec=".", stringsAsFactors=F)
+
+  if (check_inwer_file(Inwer) == FALSE) {
+    pass = FALSE
+  }  
+  
+  # add country and interviewer ID to the main data frame; merge by idno and cntry
+  # only merge when files are OK
+  if (pass == TRUE) {
+    
+    cat ("All the required variables are present, continuing with the analysis.  \n")
+    
+    Inwer_ID <- dplyr::select(Inwer, "intnum", "idno", "cntry")
+    dataset <- dplyr::left_join(dataset, Inwer_ID, by = c("idno", "cntry"))
+    
+    return (dataset)
+  }
+  else {
+    return (FALSE)
+  }
+}
\ No newline at end of file
diff --git a/components/template.R b/components/template.R
new file mode 100644
index 0000000..9403f95
--- /dev/null
+++ b/components/template.R
@@ -0,0 +1,24 @@
+ESSred <- rgb(.91, .20, .32)
+ESSgreen <- rgb(.14, .62, .51)
+ESSblue <- rgb(0, .25, .48)
+
+# now some adjacent and square colors (colortools has been removed from CRAN)
+ESS_colors_extra <- c(rgb(.44,.2,.91),rgb(.2,.91,.79),rgb(.68,.91,.2),rgb(.91,.2,.68),rgb(.91,.44,.2))
+
+ESSColors <- c(ESSred, ESS_colors_extra, ESSgreen, ESSblue)
+
+themeESS <- theme_tufte(base_size = 9, base_family = "Calibri") +
+  theme(axis.title = element_text(size = 9, face = "plain"),
+        axis.text = element_text(size = 9),
+        axis.line.x = element_line(),
+        plot.title = element_blank(),
+        legend.title = element_blank(),
+        legend.text = element_text(size = 9),
+        strip.text = element_text(size = 9, face = "bold"),
+        legend.position = "none",
+        legend.direction = "horizontal",
+        legend.box = "vertical",
+        legend.spacing = unit(0, "line"),
+        legend.key.size = unit(.75, "line"))
+linebreak <- "\\hspace{\\textwidth}"
+
diff --git a/demo_data/.~lock.inwer_file.csv# b/demo_data/.~lock.inwer_file.csv#
deleted file mode 100644
index 4c3f373..0000000
--- a/demo_data/.~lock.inwer_file.csv#
+++ /dev/null
@@ -1 +0,0 @@
-May Doušak,may,FDV,13.01.2023 14:25,file:///home/may/.config/libreoffice/4;
\ No newline at end of file
diff --git a/demo_data/inwer_file.csv b/demo_data/inwer.csv
similarity index 68%
rename from demo_data/inwer_file.csv
rename to demo_data/inwer.csv
index d4f4838..a39221b 100644
--- a/demo_data/inwer_file.csv
+++ b/demo_data/inwer.csv
@@ -26,3 +26,16 @@
 25;"SI";5
 26;"SI";6
 27;"SI";6
+28;"SI";7
+29;"SI";7
+30;"SI";7
+31;"SI";7
+32;"SI";7
+33;"SI";7
+34;"SI";7
+35;"SI";7
+36;"SI";8
+37;"SI";8
+38;"SI";8
+39;"SI";8
+40;"SI";8
diff --git a/vsi.Rmd b/vsi.Rmd
index 39942b9..39e9f1a 100644
--- a/vsi.Rmd
+++ b/vsi.Rmd
@@ -21,27 +21,15 @@ graphics: yes
 csl: ./components/apa.csl
 link-citations: yes
 params:
-  mainFile: ""
-  intFile: ""
-  version: "1.0 beta"
-  
+  mainFile: "demo_data/main.csv"
+  intFile: "demo_data/inwer.csv"
+  version: "1.0.230117"
 
 ---
 
 
 ```{r setup, include = FALSE, error=TRUE}
 library(knitr)
-#library(kableExtra)
-
-knitr::opts_chunk$set(echo = TRUE, results = "hide", message = TRUE, dev = "cairo_pdf", warning = TRUE)
-knitr::opts_chunk$set(fig.pos = 'H')
-
-options(knitr.table.format = "latex", knitr.kable.NA = "")
-
-Sys.setlocale("LC_ALL","English")
-```
-
-```{r setup2, include = FALSE,, error=T, warning=T, message=T}
 library(here) 
 library(foreign)
 library(dplyr)
@@ -49,34 +37,13 @@ library(ggplot2)
 library(lubridate)
 library(ggthemes) # theme_tufte works
 
+source('components/VSI.R')
+source('components/common.R')
 
-```
+common_defs();
 
+source('components/template.R')
 
-```{r theme, include=FALSE, error=TRUE}
-ESSred <- rgb(.91, .20, .32)
-ESSgreen <- rgb(.14, .62, .51)
-ESSblue <- rgb(0, .25, .48)
-
-# now some adjacent and square colors (colortools has been removed from CRAN)
-ESS_colors_extra <- c(rgb(.44,.2,.91),rgb(.2,.91,.79),rgb(.68,.91,.2),rgb(.91,.2,.68),rgb(.91,.44,.2))
-
-ESSColors <- c(ESSred, ESS_colors_extra, ESSgreen, ESSblue)
-
-themeESS <- theme_tufte(base_size = 9, base_family = "Calibri") +
-  theme(axis.title = element_text(size = 9, face = "plain"),
-        axis.text = element_text(size = 9),
-        axis.line.x = element_line(),
-        plot.title = element_blank(),
-        legend.title = element_blank(),
-        legend.text = element_text(size = 9),
-        strip.text = element_text(size = 9, face = "bold"),
-        legend.position = "none",
-        legend.direction = "horizontal",
-        legend.box = "vertical",
-        legend.spacing = unit(0, "line"),
-        legend.key.size = unit(.75, "line"))
-linebreak <- "\\hspace{\\textwidth}"
 ```
 
 \newpage
@@ -100,20 +67,25 @@ This tools checks the Virtual Surrounding Impression data and reports on the cas
 
 The results should always be combined with other methods of detecting undesired interviewer behaviour.
 
+## Support {-}
+
+Support is available on MyESS forums or via e-mail at may.dousak@fdv.uni-lj.si .
+  
+
 **Data check**
 
 ```{r datacheck, echo=FALSE, results='asis', error=TRUE}
 
-dataset <- read.csv2("demo_data/main.csv", dec=".", stringsAsFactors=F)
-# add interviewer file, too!
+# check files
+if (check_files(params$mainFile, params$intFile) == FALSE) {
+  cat ("  \n**Please fix the above errors and re-run the script.**")
+  knitr::knit_exit()
+}
 
 
-# include VSI functions
-
-source('components/VSI.R')
-
-# exit if data is not OK
-if (check_data(dataset) == FALSE) {
+dataset = load_files(params$mainFile, params$intFile);
+if (!(length(dataset) > 0 && dataset != FALSE)) {
+  cat ("  \n**Please fix the above errors and re-run the script.**")
   knitr::knit_exit()
 }