Once the quantitative literacy tasks are placed along the scale using the criterion of 80% (RP80), it is possible to determine to what extent the variables associated with task characteristics explain the placement of tasks along the scales. A multiple regression was run using RP80 as the dependent variable (see note 3). The independent variables were the two process variables used to characterize the prose and document literacy tasks—type of match (TOM) and plausibility of distractor (POD)—plus a newly developed measure of document readability (READ) (Mosenthal and Kirsch, 1998).⁶ Type of information (TOI) is a constant on this scale since each question requires the reader to determine an amount. In addition, we included the two process variables created for the quantitative scale—type of calculation (TOC) and operation specificity (OSP). The results are shown here in Table 3.

Table 3 shows the zero order correlation between each of the predictor variables and RP80, along with output from the regression analysis. These data reveal that operation specificity, type of calculation, and plausibility of distractor had the highest zero order correlation with RP80. In terms of the regression analysis, operation specificity received the largest standardized regression weight, followed by plausibility of distractor. Neither readability nor the other process variables were significant predictors on this set of tasks. As with the prose and document scales, it is important to note that while only some of these variables receive significant weights in the model, each is important in constructing the quantitative literacy tasks and in representing the domain. Together this set of variables accounted for 75% of the variance in RP80 values.

Multiple R = .87
Adjusted R² = .70

Easy tasks on the quantitative literacy scale tended to require readers to perform a single, relatively simple operation (addition), where either the numbers are clearly noted or provided in the text or and the operation is stipulated. Slightly more difficult tasks may require the reader to perform either an addition or a subtraction with numbers that are relatively easy to locate in the text but where the operation can be easily inferred from the wording in the question or directive. Tasks further along the quantitative scale become more varied both in terms of the type of operation they may be asked to perform, and in terms of the extent to which the numbers are embedded in more complex displays or the amount of inferencing that may be required to determine the appropriate operation that is needed. A distinguishing characteristic of the most difficult tasks along this scale is the fact that the reader is required to perform multiple operations sequentially and they must discern the features of the problem from the material and directive given.