The present study reports a two-level multivariate analysis to optimise the production of anodised aluminium oxide (Al2O3) dielectric films for zinc oxide thin-film transistor (TFTs). Fourteen performance parameters were measured and Analysis Of Variance (ANOVA) of the combined responses has been applied to identify how the Al2O3 dielectric fabrication process influences the electrical properties of the TFTs. Using this approach, the levels for the manufacturing factors to achieve optimal overall device performance have been identified and ranked. The cross-checked analysis of the TFT performance parameters demonstrated that the appropriate control of the anodisation process can have a higher impact on TFT performance than the use of traditional methods of surface treatment of the dielectric layer. Flexible electronics applications are expected to grow substantially over the next 10 years. Given the complexity and challenges of new flexible electronics components, this ‘multivariate’ approach could be adopted more widely by the industry to improve the reliability and performance of such devices.