A specific developmental cycle, termed the Matthew effects model (Bast & Reitsma, 1998; Stanovich, 2000), is thought to result in the fan spread effect.
This increasing gap is sometimes referred to as the fan spread effect.
This conceptualization is likely to strongly affect the results of any test for fan spread.
Such models include a number of properties that are particularly useful in testing for the fan spread effect (Bast & Reitsma 1997; Campbell & Kenny 1999; Shaywitz et al., 1995).
Thus, we observed no fan spread for resource-rich, low-risk population subgroups.
Much of the controversy is due to inconsistent evidence for the fan spread effect (e.g., Aarnoutse & van Leeuwe, 2000; Bast & Reitsma, 1998; Scarborough & Parker; Shaywitz et al.).
Instead of using initial test performance to select rich and poor readers, we tested for fan spread by defining rich and poor readers using exogenous child- and family-level characteristics indexing the relative magnitude of reading-related risks and inputs that a child is likely to experience during the preschool and early elementary school years.
We used growth curve modeling to test for fan spread. This allowed us to compute average reading growth trajectories for specific population subgroups defined by the exogenous background characteristics mentioned above.
When we combined the child- and family-level variables to define population subgroups, we observed a fan spread effect in the reading scores of five groups of low-performing children: (a) Blacks and Other Race or Ethnicity (including American Indian) males from the lowest SES quintile, (b) Black and Other Race or Ethnicity females from the lowest SES quintile, and (c) White males from the lowest SES quintile.