By looking at the statement, there seems to be identified a very clear and obvious relationship between cigarette smoking and making grades such that high cigarette smoking leads to lower grades and vice versa. From this, it can be observed that if cigarette smoking is increased, it will result in lower grades and if cigarette smoking is decreased, it will result in higher grades, thus effectively identifying a negative or inverse relationship between the two activities that can be estimated. Under statistical terms, the correlation (association) between cigarette smoking and making grades is found to be negative as the both the variables are found to be acting in the opposite directions.
Another important aspect which can be observed from the above statement is that it is actually the cigarette smoking activity that drives the grade making activity. In other words, level of smoking cigarettes determine the grades obtained by the students which means that the there is an impact of smoking cigarettes on making grades or smoking cigarettes causes making grades. In this way smoking cigarettes can be called as the predictor, estimator, explanatory or independent variable, whereas making grades which is the resultant variable can be called dependent variable. On graph, an inverse and linear line can be drawn for predicting this relationship between the two variables.