Come ridurre l\u2019errore di \u201cnon risposta\u201d nei campioni probabilistici: la pratica tradizionale e il modello Gallup - E.V.S.

he paper aims to discuss, through two examples, how social researchers can reduce the occurrence of the non-response bias that, if not adequately considered, can interfere with the possibility to estimate data about the population even if the research design is based on a probability sampling. Based on ex-post test, the first example shows how it is relevant also for sociologists to adopt a probability sampling. The second example aims to discuss the pros and cos of Gallup data collection method applied in the last survey of E.V.S. (European Values Study) in which is not allowed to substitute people who refuse to be interviewed or have an impediment for some reason. In conclusion, a proposal to improve the Gallup method in E.V.S. is discussed