PILE (Programme International pour le Langage de l'Enfant), the International Program for Child Language aims to describe the processes leading to the emergence of speech in infants thanks to statistic techniques. A qualitative data base was established on the basis of one minute video sequences (the statistical units) of babies aged from 3 to 9 months interacting with their mothers. The phenomenon under study is the process of speech construction. The 110 infants are belonging to seven cohorts: infants without disorders, hospitalized infants, premature infants, infants of visually deficient mothers, infants of blind mothers, infants with neurological disorders. We present a statistical study of this data base through inferential techniques (non parametric comparison tests) and factorial analyses. Some of our findings confirm or bring additional precision to clinical hypotheses concerning the impact of certain factors, such as age cohort, calendar age, infant's sex. The statistical results describing the infant's behavior while interacting with its mother indicate that the development of the baby's perceptive system is central in the construction of language precursors.