diff --git a/DESCRIPTION b/DESCRIPTION
index cdaba42..b8736b7 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -29,6 +29,6 @@ Suggests:
     knitr,
     tibble,
 VignetteBuilder: knitr
-RoxygenNote: 7.2.3
+RoxygenNote: 7.3.1
 Config/testthat/edition: 3
 Roxygen: list(markdown = TRUE)
diff --git a/NAMESPACE b/NAMESPACE
index b77180b..4152177 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -16,14 +16,17 @@ S3method(loglik,likelihood_contr_model)
 S3method(loglik,likelihood_exact_normal)
 S3method(loglik,likelihood_exact_weibull)
 S3method(loglik,likelihood_name)
+S3method(pval,hypothesis_test)
 S3method(sampler,likelihood_model)
 S3method(score,likelihood_contr_model)
 S3method(score,likelihood_exact_normal)
 S3method(score,likelihood_exact_weibull)
 S3method(score,likelihood_model)
 export(assumptions)
+export(dof)
 export(fim)
 export(hess_loglik)
+export(hypothesis_test)
 export(is_likelihood_model)
 export(likelihood_contr_model)
 export(likelihood_exact_normal)
@@ -31,6 +34,7 @@ export(likelihood_exact_weibull)
 export(likelihood_name)
 export(loglik)
 export(lrt)
+export(pval)
 export(score)
 importFrom(MASS,ginv)
 importFrom(R6,R6Class)
@@ -46,5 +50,9 @@ importFrom(numDeriv,grad)
 importFrom(numDeriv,hessian)
 importFrom(stats,nobs)
 importFrom(stats,optim)
+importFrom(stats,pchisq)
+importFrom(stats,pf)
+importFrom(stats,qnorm)
+importFrom(stats,qt)
 importFrom(stats,var)
 importFrom(utils,modifyList)
diff --git a/R/likelihood_contr_model.R b/R/likelihood_contr_model.R
index 5305835..04bda01 100644
--- a/R/likelihood_contr_model.R
+++ b/R/likelihood_contr_model.R
@@ -7,12 +7,11 @@
 #' - `score`: computes the score of the model
 #' - `hess_loglik`: computes the Hessian of the log-likelihood given
 #'  a data frame and parameters
-#' - `fim`: computes the Fisher information matrix (expectation)
 #' 
-#' It provides methods for computing the log-likelihood, score, the
-#' Hessian of log-likelihood, and the Fisher information matrix (FIM).
+#' It provides methods for computing the log-likelihood, score, and
+#' the Hessian of log-likelihood.
 #' 
-#' It also allows for different *likelihood contributions* depending
+#' It also allows for different likelihood contributions depending
 #' on the  observation type of a row in the data frame. For example,
 #' if the data frame contains both exact and interval-censored
 #' observations, then the log-likelihood contributions for exact
diff --git a/R/likelihood_name.R b/R/likelihood_name.R
index fc4605d..0c69d6e 100644
--- a/R/likelihood_name.R
+++ b/R/likelihood_name.R
@@ -68,19 +68,17 @@ assumptions.likelihood_name <- function(model, ...) {
 #' parameters.
 #' @export
 loglik.likelihood_name <- function(model, ...) {
+    x <- as.data.frame(df)[[model$ob_col]]
+    n <- length(x)
+    stopifnot(n > 0)
+
     if (is.null(model$type_col)) {
         function(df, par, ...) {
-            x <- as.data.frame(df)[[model$ob_col]]
-            n <- length(x)
-            stopifnot(n > 0, all(x > 0))
             do.call(paste0("d", model$dist_name), c(list(x), par))
             sum(do.call(paste0("d", model$dist_name), c(list(x), par), log.p = TRUE))
         }
     } else {
         function(df, par, ...) {
-            x <- as.data.frame(df)[[model$ob_col]]
-            n <- length(x)
-            stopifnot(n > 0)
             type <- as.character(df[[model$type_col]])
             ifelse(type == "left",
                    do.call(paste0("p", model$dist_name), c(list(x), par)),
diff --git a/man/dof.Rd b/man/dof.Rd
new file mode 100644
index 0000000..5fc55e6
--- /dev/null
+++ b/man/dof.Rd
@@ -0,0 +1,19 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tests.R
+\name{dof}
+\alias{dof}
+\title{Generic method for extracting the degrees of freedom from a hypothesis test}
+\usage{
+dof(x, ...)
+}
+\arguments{
+\item{x}{a hypothesis test object}
+
+\item{...}{additional arguments to pass into the method}
+}
+\value{
+degrees of freedom
+}
+\description{
+Generic method for extracting the degrees of freedom from a hypothesis test
+}
diff --git a/man/hess_loglik.likelihood_exact_normal.Rd b/man/hess_loglik.likelihood_exact_normal.Rd
index 283607e..0ffcd37 100644
--- a/man/hess_loglik.likelihood_exact_normal.Rd
+++ b/man/hess_loglik.likelihood_exact_normal.Rd
@@ -11,9 +11,6 @@ distribution}
 \item{...}{additional arguments (not used)}
 
 \item{x}{data (simple random sample)}
-
-\item{observed}{whether to return the observed fisher information, default is
-\code{TRUE}}
 }
 \description{
 Fisher information matrix generator given data \code{x} for the normal
diff --git a/man/hypothesis_test.Rd b/man/hypothesis_test.Rd
new file mode 100644
index 0000000..71a3261
--- /dev/null
+++ b/man/hypothesis_test.Rd
@@ -0,0 +1,35 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tests.R
+\name{hypothesis_test}
+\alias{hypothesis_test}
+\title{Hypothesis test structure}
+\usage{
+hypothesis_test(stat, p.value, dof, superclasses = NULL, ...)
+}
+\arguments{
+\item{stat}{test statistic}
+
+\item{p.value}{p-value}
+
+\item{dof}{degrees of freedom}
+}
+\value{
+hypothesis test
+}
+\description{
+Hypothesis test structure
+}
+\examples{
+# create a hypothesis test
+test <- hypothesis_test(stat = 1.96, p.value = 0.05, dof = 1)
+# print the test
+test
+# extract the p-value
+pval(test)
+# extract the degrees of freedom
+dof(test)
+# extract the test statistic
+stat(test)
+# check if the test is significant at the 5\% level
+is_significant_at(test, 0.05)
+}
diff --git a/man/likelihood_contr_model.Rd b/man/likelihood_contr_model.Rd
index f223a7c..e06bdde 100644
--- a/man/likelihood_contr_model.Rd
+++ b/man/likelihood_contr_model.Rd
@@ -11,13 +11,12 @@ A likelihood_model should provide the following methods:
 \item \code{score}: computes the score of the model
 \item \code{hess_loglik}: computes the Hessian of the log-likelihood given
 a data frame and parameters
-\item \code{fim}: computes the Fisher information matrix (expectation)
 }
 
-It provides methods for computing the log-likelihood, score, the
-Hessian of log-likelihood, and the Fisher information matrix (FIM).
+It provides methods for computing the log-likelihood, score, and
+the Hessian of log-likelihood.
 
-It also allows for different \emph{likelihood contributions} depending
+It also allows for different likelihood contributions depending
 on the  observation type of a row in the data frame. For example,
 if the data frame contains both exact and interval-censored
 observations, then the log-likelihood contributions for exact
diff --git a/man/lrt.Rd b/man/lrt.Rd
index 409a9b6..fe68639 100644
--- a/man/lrt.Rd
+++ b/man/lrt.Rd
@@ -4,20 +4,22 @@
 \alias{lrt}
 \title{Likelihood ratio test}
 \usage{
-lrt(ll1, ll2, data, par1, par2, df = NULL, ...)
+lrt(model1, model2, data, par1, par2, dof = NULL, ...)
 }
 \arguments{
-\item{data}{data}
+\item{data}{the data which the likelihood models are fitted to}
 
-\item{par1}{parameters for first model}
-
-\item{par2}{parameters for second model}
+\item{dof}{degrees of freedom}
 
 \item{...}{additional arguments}
 
-\item{model1}{first likelihood model}
+\item{null}{the null (simpler) likelihood model}
+
+\item{alt}{the more complicated model}
+
+\item{null_par}{parameters for null model}
 
-\item{model2}{second likelihood model}
+\item{alt_par}{parameters for alternative model}
 }
 \value{
 likelihood ratio test
diff --git a/man/pval.Rd b/man/pval.Rd
new file mode 100644
index 0000000..9d9c828
--- /dev/null
+++ b/man/pval.Rd
@@ -0,0 +1,19 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tests.R
+\name{pval}
+\alias{pval}
+\title{Generic method for extracting the p-value from a hypothesis test}
+\usage{
+pval(x, ...)
+}
+\arguments{
+\item{x}{a hypothesis test object}
+
+\item{...}{additional arguments to pass into the method}
+}
+\value{
+p-value
+}
+\description{
+Generic method for extracting the p-value from a hypothesis test
+}
diff --git a/man/pval.hypothesis_test.Rd b/man/pval.hypothesis_test.Rd
new file mode 100644
index 0000000..1fce0c9
--- /dev/null
+++ b/man/pval.hypothesis_test.Rd
@@ -0,0 +1,19 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tests.R
+\name{pval.hypothesis_test}
+\alias{pval.hypothesis_test}
+\title{p-value method for hypothesis tests}
+\usage{
+\method{pval}{hypothesis_test}(x, ...)
+}
+\arguments{
+\item{x}{a hypothesis test}
+
+\item{...}{additional arguments}
+}
+\value{
+p-value
+}
+\description{
+p-value method for hypothesis tests
+}