diff --git a/DESCRIPTION b/DESCRIPTION
index 08cc72d0..c87d18e7 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: heemod
 Title: Models for Health Economic Evaluation
-Version: 0.7.0
+Version: 0.7.1
 Authors@R: c(
     person("Antoine", "Filipovic-Pierucci", email = "pierucci@gmail.com", role = c("aut", "cre")),
     person("Kevin", "Zarca", email = "kevin.zarca@urc-eco.fr", role = "aut"),
diff --git a/NEWS.md b/NEWS.md
index 9d80c51c..bf13085d 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,9 @@
+# heemod 0.7.1
+
+## Bugfixes
+
+  * Fixed an error resulting in incorrect covariance analysis results when relations between values and parameters were negative.
+
 # heemod 0.7.0
 
 ## Breaking changes
diff --git a/R/covariance.R b/R/covariance.R
index 125c51c7..798ef0d9 100644
--- a/R/covariance.R
+++ b/R/covariance.R
@@ -30,14 +30,16 @@ compute_cov <- function(psa) {
     ))
     res <- stats::lm(form, data = data_trans)
     
-    tot <- sum(stats::coef(res)[-1])
+    val <- abs(stats::coef(res)[-1])
+    tot <- sum(val)
     r2 <- summary(res)$r.squared
     if (r2 < .99) {
       warning(sprintf(
-        "Only %.0f%% of variance explained, results may be inaccurate."
+        "Only %.0f%% of variance explained, results may be inaccurate.",
+        r2 * 100
       ))
     }
-    as.data.frame(as.list(stats::coef(res)[-1] / tot * r2))
+    as.data.frame(as.list(val / tot * r2))
   }
   
   psa$psa %>% 
diff --git a/inst/examples/example_update.R b/inst/examples/example_update.R
index 23ee6ff4..67dabf5f 100644
--- a/inst/examples/example_update.R
+++ b/inst/examples/example_update.R
@@ -44,7 +44,7 @@ res <- run_model(
 
 # generating table with new parameter sets
 new_tab <- data.frame(
-  age_init = 40:80
+  age_init = 40:45
 )
 
 # with run_model result
@@ -55,7 +55,7 @@ summary(ndt)
 # using weights
 
 new_tab2 <- data.frame(
-  age_init = 40:80,
+  age_init = 40:45,
   .weights = runif(41)
 )
 ndt2 <- update(res, newdata = new_tab2)
diff --git a/man/update-model.Rd b/man/update-model.Rd
index 76c24847..a841638f 100644
--- a/man/update-model.Rd
+++ b/man/update-model.Rd
@@ -110,7 +110,7 @@ res <- run_model(
 
 # generating table with new parameter sets
 new_tab <- data.frame(
-  age_init = 40:80
+  age_init = 40:45
 )
 
 # with run_model result
@@ -121,7 +121,7 @@ summary(ndt)
 # using weights
 
 new_tab2 <- data.frame(
-  age_init = 40:80,
+  age_init = 40:45,
   .weights = runif(41)
 )
 ndt2 <- update(res, newdata = new_tab2)