I have a data frame as below:

```
df <- data.frame(Staff = c("Jack", "Ruth", "Michael", "Ruth", "Jack", "Jack", "Ruth", "Michael"), 
                 Client = c("Julie", "Julie", "Julie", "Julie", "Julie", "Candice", "Candice", "Candice"),
                 Assessment = c(1, 2, 2, 1, 7, 4, 1, 1), 
                 Staff_avg_by_client = c(4, 1.5, 2, 1.5, 4, 4, 1, 1))

```