...The teams were able to replicate the results of less than half of the tested experiments. That rate is in keeping with that found by other large-scale attempts to reproduce scientific findings. But the latest work is unique in focusing on papers that use specific methods and in examining the research output of a specific country, according to the research teams...

They ended up selecting three of these methods: an assay of cell metabolism, a technique for amplifying genetic material and a type of maze test for rodents. Then the authors randomly selected biomedical papers that relied on those methods and were published from 1998 to 2017 by research teams in which at least half the contributors had a Brazilian affiliation....

The authors judged a paper’s replicability by five criteria, including whether at least half of the replication attempts had statistically significant results in the same direction as the original paper. Only 21% of the experiments were replicable using at least half of the applicable criteria...

Marcelo Mori, a biologist at the State University of Campinas in Brazil, agrees. “Exact replication of an experiment is particularly challenging in the life sciences,” he says. “Living organisms, such as rodents and cell cultures, can respond differently when exposed to environmental variations like temperature, diet, microbiota, or culture medium composition.” Reagents, such as antibodies, can exhibit batch-to-batch variation, he adds...

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