1. A method for estimating a cost and a duration for migrating a computer application from a source platform to a target platform, the method comprising: a computer receiving a request to estimate the cost and the duration for migrating the computer application, the request including an indication of a first, second or third assessment type; and the computer receiving specification of (a) a plurality of migration attributes of the computer application, the plurality of migration attributes being associated with the first assessment type, (b) a first subset of migration attributes that is less than all of the plurality of migration attributes, the first subset of migration attributes being associated with the second assessment type, the second assessment type being less accurate than the first assessment type, or (c) a second subset of migration attributes that is less than all of the first subset of migration attributes, the second subset of migration attributes being associated with the third assessment type, the third assessment type being less accurate than the second assessment type, the plurality of migration attributes including a source code corresponding to the computer application, the first subset of migration attributes including a count of a number of lines in the source code, and the second subset of migration attributes including a type of operating system on which the computer application executes; the computer receiving specification of a set of tasks required for the migration; the computer determining, an average cost of completing each of the task and an average duration for completing each of the task; and the computer estimating the cost and the duration for migrating the computer application based at least in part on the average cost of completing each task, the average duration for completing each task and one of the plurality of migration attributes, the first subset of migration attributes and the second subset of migration attributes.