Final answer:
Early estimates before project specifications are less accurate than later estimates informed by thorough data analysis. The process of estimation evolves from general guesstimates to precise calculations as project details become clearer and more data is collected.
Step-by-step explanation:
An estimate made before the specifications have been signed off on by the client is likely to be less accurate than an estimate made with sufficient data. During the initial stages, estimates such as guesstimates, order-of-magnitude approximations, or Fermi calculations are based on general experience or theoretical understanding, without detailed empirical data. As a result, such premature estimates are often less reliable due to a greater degree of uncertainty and a lack of specific information.
When more data is collected and the project specifications are clearer, the accuracy of estimates typically improves. Therefore, detailed analysis informed by sufficient data leads to more precise and dependable cost and duration estimates. Mathematical models and formulas often depend on the precision of the input quantities; having accurate data ensures the estimates are closer to the actual values needed for scientific work, which requires high levels of detail.
Furthermore, as one develops skills in physics and engineering, experience with quantitative thinking and familiarity with dimensions and units becomes crucial for making accurate estimates. Practice and experience in this area result in better judgement and sanity checks on calculations and proposals, ultimately contributing to more successful project outcomes.