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This study pushes our understanding of research reliability by reproducing and replicating claims from 110 papers in leading economic and political science journals. The analysis involves computational reproducibility checks and robustness assessments. It reveals several patterns. First, we uncover a high rate of fully computationally reproducible results (over 85%). Second, excluding minor issues like missing packages or broken pathways, we uncover coding errors for about 25% of studies, with some studies containing multiple errors. Third, we test the robustness of the results to 5,511 re-analyses. We find a robustness reproducibility of about 70%. Robustness reproducibility rates are relatively higher for re-analyses that introduce new data and lower for re-analyses that change the sample or the definition of the dependent variable. Fourth, 52% of re-analysis effect size estimates are smaller than the original published estimates and the average statistical significance of a re-analysis is 77% of the original. Lastly, we rely on six teams of researchers working independently to answer eight additional research questions on the determinants of robustness reproducibility. Most teams find a negative relationship between replicators' experience and reproducibility, while finding no relationship between reproducibility and the provision of intermediate or even raw data combined with the necessary cleaning codes.
Ocean Drilling Program Site 1085 provides a continuous marine sediment record off southern South West Africa for at least the last three and half million years. The n-alkane partial derivative(13) C record from this site records changes in past vegetation and provides an indication of the moisture availability of SW Africa during this time period. Very little variation, and no apparent trend, is observed in the n-alkane delta C-13 record, suggesting stable long-term conditions despite significant changes in East African tectonics and global climate. Slightly higher n-alkane delta C-13 values occur between 3.5 and 2.7 Ma suggesting slightly drier conditions than today. Between 2.5 and 2.7 Ma there is a shift to more negative n-alkane delta C-13 values suggesting slightly wetter conditions during a similar to 0.2 Ma episode that coincides with the intensification of Northern Hemisphere Glaciation (iNHG). From 2.5 to 0.4 Ma the n-alkane delta C-13 values are very consistent, varying by less than +/- 0.5 parts per thousand and suggesting little or no long-term change in the moisture availability of South West Africa over the last 2.5 million years. This is in contrast to the long-term drying trend observed further north offshore from the Namib Desert and in East Africa. A comparison of the climate history of these regions suggests that Southern Africa may have been an area of long-term stability over the last 3.5 Myrs.