What are the differences between bottom up and top down estimating approaches?

Then, what is the difference between top down and bottom up approach?

Difference between Top-downandBottom-up Approach. The algorithms are designedusingtwo approaches that are the top-downandbottom-up approach. In thetop-downapproach, the complex module is divided intosubmodules. On theother hand, bottom-up approachbegins with elementarymodules and then combine themfurther.

Secondly, what is a bottom up estimate? Bottom-up estimating is aprojectmanagement technique in which the people who are going to dothework take part in the estimating process. Settingtheestimates of the amount of work, duration and cost at thetasklevel lets you combine them into estimates ofhigher-leveldeliverables and the project as a whole.

Consequently, what is top down and bottom up estimating?

Top Down estimating is a projectestimatingtechnique whereby the overall project isestimated first, andindividual tasks are apportioned from it.Top Down is theopposite of Bottom Up Estimating,whereby individual tasksare estimated first and “rolledup” into theoverall projectestimate.

Which type of cost estimating is the preferred most accurate method?

Three-point Estimation The three estimates are the mostlikelycost, the pessimistic cost, and theoptimisticcost. It reduces bias, risk, and uncertainty fromtheestimation. It is more accurate than theanalogousand parametric estimating techniques. This is themostaccurate technique of all themethodspresented.