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language and Java to be the experimental one. The values of all other state
variables should stay the same (e.g., application experience, programming
environment, and type of problem). Then you can be sure that any difference
in productivity is attributable to the change in language. This type of experi-
ment was carried out at NASA’s Goddard Space Flight Center to support the
decision to move from the FORTRAN language to Ada. The experiments
revealed that productivity in Ada did not exceed FORTRAN until the third
use of Ada, when programmers began to use Ada appropriately.
4.1.4 Threats to Validity
We have a ...