Nu se pretează? Nu contează! La noi puteți returna bunurile în 30 de zile
Cu un voucher cadou nu veți da greș. În schimbul voucherului, destinatarul își poate alege orice din oferta noastră.
30 de zile pentru retur bunuri
An Observational study is an empiric investigation of the effects caused by a treatment, policy , or intervention in which it is not possible to assign subjects at random to treatment or control, as would be done in a controlled experiment. Observational studies are common in most fields that study the effects of treatments on people.§The second edition of