Quantity surveyor estimates quantities and costs of building materials and labour required and prepares bills of quantities. He/she visits the site periodically to estimate the value of work completed prior to issuing certificates for interim payments to the contractor and examines the completed project, makes measurements and calculations, adjusts any variations from the original contract and assesses the final cost. He/she may analyse comparative advantages and estimate costs of using different methods of construction or different materials, be involved in contract management to ensure compliance, and may also assist with tender preparation and submission and prepare or check final accounts.