diff --git a/09-Item-Response-Theory.Rmd b/09-Item-Response-Theory.Rmd
index 744d4053..5c3ece2a 100644
--- a/09-Item-Response-Theory.Rmd
+++ b/09-Item-Response-Theory.Rmd
@@ -953,7 +953,7 @@ $$
 
 where $\sigma^2(\theta)$ is the variance of theta, which is fixed to one in most IRT models.\index{item response theory}\index{item response theory!information}\index{reliability}\index{item response theory!theta}
 
-The [`petersenlab`](https://github.com/DevPsyLab/petersenlab) package [@R-petersenlab] contains the `reliabilityiRT()` function that estimates the amount of [reliability](#irtReliability) an item or a measure provides as function of its information and the variance of people's construct levels ($\theta$).\index{petersenlab package}\index{item response theory}\index{item response theory!information}\index{reliability}\index{item response theory!theta}
+The [`petersenlab`](https://github.com/DevPsyLab/petersenlab) package [@R-petersenlab] contains the `reliabilityIRT()` function that estimates the amount of [reliability](#irtReliability) an item or a measure provides as function of its information and the variance of people's construct levels ($\theta$).\index{petersenlab package}\index{item response theory}\index{item response theory!information}\index{reliability}\index{item response theory!theta}
 
 ```{r, eval = FALSE, class.source = "fold-hide"}
 reliabilityIRT <- function(information, varTheta = 1){