diff --git a/Pipfile b/Pipfile
new file mode 100644
index 0000000..51f608c
--- /dev/null
+++ b/Pipfile
@@ -0,0 +1,12 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+matplotlib = "*"
+
+[dev-packages]
+
+[requires]
+python_version = "3.9"
diff --git a/covidrisk.py b/covidrisk.py
index c553ff1..0123bf3 100644
--- a/covidrisk.py
+++ b/covidrisk.py
@@ -29,9 +29,9 @@ def p_meet_positive_bayes(groupsize:int):
 
 def plot_data(data):
     plt.plot(data)
-    plt.title("probability of meeting a covid positive in groupsize of n")
+    plt.title("likelihood of having a covid positive in groupsize of n")
     plt.xlabel("group size / n")
-    plt.ylabel("probability")
+    plt.ylabel("probability / %")
     plt.grid(linestyle='--', linewidth='0.1')
     plt.show()