Related Experiment Video
Updated: May 1, 2026

Barnes Maze Testing Strategies with Small and Large Rodent Models
Published on: February 26, 2014
Logrank-type tests with presmoothing
M Amalia Jácome1, Ignacio López-de-Ullibarri2
1Department of Mathematics, Faculty of Science, University of A Coruña, Campus da Zapateira, 15005 A Coruña, Spain.
Abstract:
The logrank test is the most popular choice for testing the equality of two survival distributions with time-to-event data. It is based on the comparison of the Nelson-Aalen estimates of the corresponding cumulative hazard functions. The improvements of the logrank test in the literature have been accomplished using weighted logrank tests, with the weight chosen appropriately to maximize power. Notwithstanding, power also depends on the efficiency of the estimation of the cumulative hazard function. The presmoothed estimator has been shown to be more efficient than the Nelson-Aalen estimator under some general assumptions. We introduce a new logrank-type test that, instead of the Nelson-Aalen estimator, is based on its presmoothed counterpart. An extensive simulation study has been conducted to compare the performance of this new test with the classical one. This study shows that the new test has the proper size under the null hypothesis, while improving the power over a wide range of alternatives. The new test is illustrated with several real data examples.
Related Concept Videos
Ranks
Wald-Wolfowitz Runs Test II
For binary data, runs are identified using symbols such as + and −, or equivalently, 1s and...
Wald-Wolfowitz Runs Test I
The test works...
The Mantel-Cox Log-Rank Test
Testing a Claim about Population Proportion
There are two methods of testing a claim about a population proportion: (1) Using the sample proportion from the data where a binomial distribution is approximated to the normal distribution and (2) Using the binomial probabilities calculated from the data.
The first method uses normal distribution as an approximation to the binomial distribution. The requirements are as follows: sample size is large...
Friedman Two-way Analysis of Variance by Ranks

