# Ranking based of number of items and value

How do you avoid the issue of an item with a single 5-star rating getting a higher average rating than one with (99 5-star ratings and one 4-star rating)? How do you properly rank based on average star and frequency?

Sample name|No.of raters|star rating|average star rating
a          |10          |5          |5
b          |100         |5,4        |4.8
c          |1000        |5,3        |4.5
d          |1500        |4          |4
e          |2000        |5,4,3      |4.2

• While it's somewhat different in form, there's one suggested approach in this answer – Glen_b Mar 16 '15 at 5:04

$$\bar s = {\sum s_{i} \over n},$$
but it's better to add a correction for total number of answers given. One way to correct is to add some "dummy" one star (e.g. $10$), so
$$\bar s' = {\sum s_{i} + 10 \over n + 10}.$$