diff --git a/s4.py b/s4.py
new file mode 100755
index 0000000..796db7f
--- /dev/null
+++ b/s4.py
@@ -0,0 +1,66 @@
+'''
+Step 4
+'''
+# -*- coding:utf-8 -*-
+#!/usr/bin/env python
+from __future__ import print_function
+from base import Lo, create_csv
+import os
+import csv
+import sys
+
+los = Lo()
+
+xmodels = {
+    'IMSf': {}, 'IMSD': {}, 'IMHf': {}, 'IMHD': {}, 'IFSf': {}, 'IFSD': {},
+    'IFHf': {}, 'IFHD': {}, 'CMSf': {}, 'CMSD': {}, 'CMHf': {}, 'CMHD': {},
+    'CFSf': {}, 'CFSD': {}, 'CFHf': {}, 'CFHD': {}, 'PMSf': {}, 'PMSD': {},
+    'PMHf': {}, 'PMHD': {}, 'PFSf': {}, 'PFSD': {}, 'PFHf': {}, 'PFHD': {},
+}
+fs = ('Case1_LS.csv', 'Case1_Gender.csv', 'Case1_Level.csv', 'Case1_SciF.csv')
+
+
+def get_match_all():
+    result = {}
+    fpath = os.path.join(os.getcwd(), 'build', 'part3', 'step3_match_all.csv')
+    with open(fpath, 'rb') as f:
+        rows = csv.reader(f)
+        for r in rows:
+            result[r[0]] = r[1].split(',')
+    return result
+
+
+def get_weight(xmodel):
+    result = {}
+    fpath = os.path.join(os.getcwd(), 'build', 'part2', '%s-3.csv' % xmodel)
+    with open(fpath, 'rb') as f:
+        rows = csv.reader(f)
+        for r in rows:
+            result[r[0]] = [r[1], r[2], r[3], r[4], r[5], r[6]]
+    return result
+
+
+def produce(match_all):
+    for ii in xmodels.keys():
+        rows = []
+        weight = get_weight(ii)
+        for lo in sorted(los.los):
+            is_matched = 1 if lo in match_all[ii] else 0
+            r = [lo, is_matched, los.los[lo]['weight']]
+            if is_matched:
+                r += weight[lo][1:]
+            rows.append(r)
+        _f = '%s-step4.csv' % ii
+        create_csv(_f, rows, directory='part4')
+
+
+def main(*argv):
+    ma_data = get_match_all()
+    produce(ma_data)
+
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1:
+        main(sys.argv[1:])
+    else:
+        main()