Program readability: procedures versus comments

A 3×2 factorial experiment was performed to compare the effects of procedure format (none, internal, or external) with those of comments (absent or present) on the readability of a PL/1 program. The readability of six editions of the program, each having a different combination of these factors, was inferred from the accuracy with which students could answer questions about the program after reading it. Both extremes in readability occurred in the program editions having no procedures: without comments the procedureless program was the least readable and with comments it was the most readable