diff --git a/docs/statlab_corr_spearman_rho.rst b/docs/statlab_corr_spearman_rho.rst
index 9e499772..d898d5eb 100644
--- a/docs/statlab_corr_spearman_rho.rst
+++ b/docs/statlab_corr_spearman_rho.rst
@@ -146,7 +146,7 @@ More Details
 *************
 
 Assume that :math:`Y_{i1} \sim \mathcal{D}`.
-For continuous :math:`Y_{i1}`, if we can assume that :math:`P(S_{i1}=0)=1`, 
+For continuous :math:`Y_{i1}`, if we can assume that :math:`P(S_{i2}=1)=1` for all :math:`i`, 
 then :eq:`eq_rank` can be simplified as :math:`R_{i1} = S_{i1}+1`.
 For a given sample size :math:`n`, and :math:`r \in \{1, \ldots, n\}`, the pmf of :math:`R_{i1}` is 
 :math:`P(R_{i1} = r) = \frac{1}{n}`, which does not depend on :math:`r` or :math:`\mathcal{D}` [4]_.
diff --git a/project.toml b/project.toml
index 39892b3a..c111ccac 100644
--- a/project.toml
+++ b/project.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mtbp3"
-version = "0.2.20"
+version = "0.2.21"
 dependencies = [
   "pathlib",
   "pandas",
diff --git a/pyproject.toml b/pyproject.toml
index e17691fb..1e2dc357 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "mtbp3"
-version = "0.2.20"
+version = "0.2.21"
 description = "my tool box"
 authors = ["Y. Hsu"]
 license = "GNU General Public License v3.0"
diff --git a/setup.py b/setup.py
index f2c5aa65..4d3fd28f 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@
 
 setup(
     name='mtbp3',
-    version='0.2.20', # https://packaging.python.org/en/latest/specifications/version-specifiers/#version-specifiers 
+    version='0.2.21', # https://packaging.python.org/en/latest/specifications/version-specifiers/#version-specifiers 
     author='Y. Hsu',
     author_email='yh202109@gmail.com',
     description='My tool box in Python',