diff --git a/ks_test_all_timepoints.R b/ks_test_all_timepoints.R
index a1a0936..8581de5 100644
--- a/ks_test_all_timepoints.R
+++ b/ks_test_all_timepoints.R
@@ -10,6 +10,10 @@ getwd()
 ############################################################
 # source data
 source("read_data.R")
+
+# clear unwanted variables
+rm(my_data)
+
 ############################################################
 #===================================
 # output: KS test for cumulated time
diff --git a/ks_test_time.R b/ks_test_time.R
index 4df3778..0b6022c 100644
--- a/ks_test_time.R
+++ b/ks_test_time.R
@@ -10,6 +10,10 @@ getwd()
 ############################################################
 # source data
 source("read_data.R")
+
+# clear unwanted variables
+rm(my_data)
+
 ############################################################
 #===================================
 # output: KS test at each timepoint
diff --git a/read_data.R b/read_data.R
index cc7daea..fc0a0c1 100755
--- a/read_data.R
+++ b/read_data.R
@@ -19,10 +19,14 @@ outdir_stats = "~/git/covid_data/output/stats/"
 
 #==========================================================
 # input data files
+infile_covid = paste0(datadir,"/covid19_v3.csv")
+
 infile_icu_wf = paste0(datadir,"/icu_covid_wf_v3.csv")
 infile_icu_lf = paste0(datadir,"/icu_covid_lf_v3.csv")
 #%%========================================================
-# read file
+# read files
+my_data = read.csv(infile_covid, stringsAsFactors = F) 
+
 wf_data = read.csv(infile_icu_wf , stringsAsFactors = F) 
 dim(wf_data)
 
diff --git a/stats_paired.R b/stats_paired.R
index e37c99c..ffeeeca 100755
--- a/stats_paired.R
+++ b/stats_paired.R
@@ -10,6 +10,10 @@ getwd()
 ############################################################
 # source data
 source("read_data.R")
+
+# clear unwanted variables
+rm(my_data)
+
 ############################################################
 #=========================
 # output: paired_analysis
diff --git a/stats_unpaired.R b/stats_unpaired.R
index 73600d5..c9cac4d 100755
--- a/stats_unpaired.R
+++ b/stats_unpaired.R
@@ -10,6 +10,10 @@ getwd()
 ############################################################
 # source data
 source("read_data.R")
+
+# clear unwanted variables
+rm(my_data)
+
 ############################################################
 #============================
 # Output: unpaired analysis
diff --git a/summary_stats_time.R b/summary_stats_time.R
index be1a9de..fb4b584 100755
--- a/summary_stats_time.R
+++ b/summary_stats_time.R
@@ -10,6 +10,10 @@ getwd()
 ############################################################
 # source data
 source("read_data.R")
+
+# clear unwanted variables
+rm(my_data)
+
 ############################################################
 #===============================
 # output: summary stats by time
diff --git a/summary_stats_time_outcome.R b/summary_stats_time_outcome.R
index 8511d9f..8fb6e8c 100755
--- a/summary_stats_time_outcome.R
+++ b/summary_stats_time_outcome.R
@@ -10,6 +10,10 @@ getwd()
 ############################################################
 # source data
 source("read_data.R")
+
+# clear unwanted variables
+rm(my_data)
+
 ############################################################
 #=========================================
 # output: summary stats by time + outcome