Ok, thank you so much! I'll tell you more information of the data:

The sample includes all those people who have between 18 and 22 years old and have finished secondary school. The period under study are the 10 years between 2000 and 2010.

The dependent variable is a binary variable, which takes the value of 1 if the youth attend to high school and 0 otherwise.

The independents variables are:

**Logarithm of family income**

**Parents education**, which is represented by 3 binary variables: **primary school**,** secondary school** and **high school**; each of them tooks the value of 1 if at least one of the parents has finished the correspondent level of education, and 0 otherwise. The omitted variable is "no education".

**Sex**, which is a binary variable that takes the value of 1 if the youth is boy and 0 if it is girl.

**Age**, which is a control variable.

What I'm searching for is to determine if those factors that are beyond the control of the youth (sex, family income, etc.) are affecting his probability of attend high school.

But, for example, the coefficients corresponding to family income resulted to be significant one year, not significant at the next year, and so on. So, what can I say about the relationship between family income and the probability of attending high school?

Thank you very much again!