Return std instead of cov from reliability analysis

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (817ee76) 98.27% compared to head (14ce9a8) 98.27%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #158 +/- ## ========================================== - Coverage 98.27% 98.27% -0.01% ========================================== Files 27 27 Lines 1045 1042 -3 ========================================== - Hits 1027 1024 -3 Misses 18 18 ```

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