how does a linear equation evolve over time how do you know if you have an interaction variable? how do you find the interaction of each variable and test the linear effect of each? how does the regressor interact with the dependent variable how is the interaction coefficient determined on a linear model of time? how does the linear effect of presentation regress how does a linear regression work how does the interaction effect evolve over time how is the relationship between number of presentations and day's value how do you test an interaction term of a linear model how does the interaction term change over time how does the slope evolve over time how do linear regression models work can the number of presentations be a dependent variable when to model a linear effect from the number of presentations? how does a linear model of a slope affect regressors? how many variables does it take to form an association model how does the interaction model of presentations develop how do you tell if there is a linear effect of the number of presentations and the duration of each day how does a linear model of time change over time?