The STARTS model, created by David Kenny and Alex Zautra in 2001, is a tool for analyzing the dynamics of constructs. According to Jean Frisou and Hélène Yildiz, this model differs from the LSTM model in its specific structure. It is based on a single element, denoted yt, influenced by a stable trait, an autoregressive trait evolving over time, and a measurement error. The autoregressive trait is linked to its previous value at time t-1 and to a situational factor dt. To identify the STARTS model, it is necessary to perform at least four repeated measurements, although its estimation can sometimes be complex. Indeed, when the coefficients a approach 0, the autoregressive traits βt become independent variables that are difficult to distinguish from the residual terms dt. Conversely, when the coefficients a approach 1, the factors βt group together into a single latent variable, making it difficult to distinguish from the durable trait.