It was aimed to reveal the informal statistical inferences of primary school students on the concept of variability. A phenomenographic research approach was adopted. A task was adapted and used as a data collection tool. Clinical interviews were conducted with 20 primary school students from each grade level. Data were analyzed within the context of the analysis framework hierarchy of development for variability. The results showed that the highest number of students were at Level 1, followed by those who are at Level 0. It can also be seen that the numbers of the students who are at Level 3 and Level 4 are close to each other and smaller than the number of students at Level 1. In addition, it is seen that there is no 1st grade student at Level 4 and that the majority of the students at Level 3 and Level 4 are 3rd and 4th graders. One out of four students had difficulty in informal statistical inferences on the concept of variability. Informal statistical inferences on the concept of variability of three out of every four students, albeit at different levels, drew attention.