email score
             <chr> <int>
 1 [email protected]     4
 2 [email protected]     3
 3 [email protected]     3
 4 [email protected]     4
 5 [email protected]     1
 6 [email protected]     4
 7 [email protected]     5
 8 [email protected]     5

email score     mean        sd
            <chr> <int>    <dbl>     <dbl>
1 [email protected]     4 4.000000        NA
2 [email protected]     3 3.500000 0.7071068
3 [email protected]     3 3.333333 0.5773503
4 [email protected]     4 3.500000 0.5773503
5 [email protected]     1 1.000000        NA
6 [email protected]     4 2.500000 2.1213203
7 [email protected]     5 3.333333 2.0816660
8 [email protected]     5 3.750000 1.8929694