Audit Planning and The Reliability of Audit Evidence: Evidence from External Audit Firms in Ghana

The integrity of corporate financial reporting relies heavily on the quality of external independent examinations, yet the operational mechanisms through which preliminary audit planning directly dictates the reliability of gathered audit evidence remain under-explored. Drawing on Agency Theory, the Policeman Theory of Auditing, and Limperg's Inspired Confidence Theory, this study examines how systematic audit planning affects the reliability of audit evidence within external audit firms. Using a quantitative cross-sectional survey design, data was gathered via structured questionnaires from 72 active audit professionals across selected external audit firms in Ghana. The study estimates multiple linear regression models of evidence reliability as a function of risk assessment, resource allocation, and operational time scheduling. The results indicate that comprehensive audit planning explains 55.1% of the variance in audit evidence reliability. Specifically, rigorous risk assessment practices (β=0.441,p<0.05) and strategic human and technical resource allocation (β=0.312,p<0.05) exhibit the strongest positive impacts on obtaining high-quality, verifiable audit evidence. Time scheduling, however, does not yield a statistically significant direct impact on evidence internal quality at conventional levels (β=0.124,p=0.052). The findings demonstrate that dynamic risk profiling and optimal personnel matching are critical strategic dimensions for preventing failures in evidence collection, preserving audit quality, and safeguarding public market trust.