Variables considered in development appraisal sometimes assume character and behavioural distortions and magnitude. Thus, this study examined whether there is significant difference between predicted variable values as used by appraisers and actual values on the execution of the project. In attempt to achieve this, the study surveyed a cross section of 36 estate surveying and valuation firms’ reports and their clients in Uyo. Analysis of Variance (ANOVA) at 5% level of significant was used to confirm the difference. The study found that there is significant difference between the estimated variable values as adopted by development appraisers in their reports and the actual or realised values of such variables on execution/completion of the projects. It further revealed that development period had the highest difference between the estimated and actual period followed by interest rate adopted and cost of construction. It was suggested that henceforth, appraisers should provide their clients with an understanding of fluctuation in these variables and point out that development appraisals were prepared on assumptions of economic stability.