```r
data_means <- list()
for (name in names(loop_data)) {
  data_means[name] = mean(loop_data[[name]])
}

str(data_means)
```

```
## List of 4
##  $ a: num -0.383
##  $ b: num 0.417
##  $ c: num 0.855
##  $ d: num -20.9
```