In other sections of the NRP report, such as the sections on phonics and phonemic awareness, the NRP listed studies that were excluded from its analysis. This was not done for the section on fluency. We do not know, therefore, which excluded studies were simply missed and which were rejected, nor do we know the specific rationale for their rejection.

In table 2, I present an "expanded" set of SSR studies in which tests of reading comprehension were used. Many of the studies summarized in table 2 meet the four criteria of the NRP and were apparently missed, but there were some "violations": A few were done with students slightly older than the age limit imposed by the NRP; in all cases, the subjects were undergraduate college students. Subjects in some of the studies were students of English as a second language.⁶ In several studies, students read in Spanish, not English; in these cases, the students were native speakers of Spanish. Finally, some studies were not published in refereed journals.

Table 2 summarizes the results of these studies. It includes studies included by the NRP as well as those that the NRP did not include.

TABLE 2

Duration of Treatment and Outcomes of SSR Studies: Expanded Set⁷

In the studies in table 2, SSR students did as well or better than comparison students in 50 out of 53 comparisons. For longer term studies (those longer than one year), SSR students were superior in eight out of ten studies, and there was no difference in the other two. Moreover, there are plausible reasons why the results were not even more positive: In one study carried out by Isabel Schon, Kenneth Hopkins, and Carol Vojir, there was no difference between SSR students and comparison groups, but only five of the eleven SSR teachers actually carried out SSR conscientiously.⁸ The classes taught by these five achieved significantly better gains.

In a study by Ruth Cline and George Kretke, another study showing no difference, subjects were junior high school students who were reading two years above grade level, and probably had already established a reading habit.⁹ Similarly, in Zephaniah Davis' study of eighth graders, SSR helped medium level readers but not better readers.¹⁰ SSR appears to be most effective for less mature readers, its aim being to interest them in outside reading. Those who are already dedicated readers will not show dramatic gains. It is doubtful, for example, that readers of this paper will improve if they add to their daily schedule an extra 10 minutes of reading.

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