Since we had no information regarding the size of the businesses of the owners, the vast majority of them were classified in sub-class IVab while some of them would have been more properly classified in class I-II.
On the other hand, in a previous study (de Seve, Bouchard and Hamel 1995b), we have examined the historical homogeneity of the classes distinguished in terms of social mobility and its results suggested that the EGP classes are indeed homogeneous with two exceptions: in sub-class IVab, it would have been useful to distinguish the "traditional" craftsmen ("artisans") from the other small owners, and category V-VI hides a certain amount of mobility by regrouping the foremen and the skilled manual workers.
In 1851, almost all (91.8%) of the sons were in the two "rural" subclasses of the primary sector (sub-classes IVc and VIIb) and the other categories were almost empty: 1% in classes I to III, 2.1% in the sub-class of the small business owners IVab, and 5.2% in manual industrial occupations (V-VI and VIIa) (first column of Table 1).
Two classes seem to evolve in a less regular manner than the others: after 1891, the small business owners' sub-class (IVab) does not seem to expand, and the rural labourers (VIIb) remains quite unchanged between 1871 and 1951.
b) intermediate stratum: classes III, IVab, V and VI,
- three factors consider "inheritance" or "stability" within the different classes: a general term (IN1) affecting all classes, a particular term (IN2) for the three categories containing owners (I-II, IVab and IVc) and, lastly, a specific one (IN3) for the category of "farmers" (IVc); usually, these parameters are positive because they measure the well known tendency of sons to occupy the same position as their father;
- finally, two factors express particular "affinities", whether they be negative (AF1) or positive (AF2), between some classes; AF1 describes the difficulty of mobility between classes I-II and VIIb, while AF2 reflects the easier mobility some other classes (between I-II and IIIab or IVab, between IVab and IVc, from IVab or V-VI to VIIa, from VIIa to V-VI and from VIIb to VIIa).