Solution Evaluation Metrics (SQA National 5 Computing Science): Revision Note

Solution evaluation

What is solution evaluation?

• Solution evaluation is the stage after testing where you judge how well the final program, database or website meets the original requirements

• Evaluation links back to the iterative development process by identifying improvements for the next cycle

• Evaluation focuses on three main factors:

  • Fitness for purpose

  • Efficient use of coding constructs

  • Robustness

Fitness for purpose

• A solution is fit for purpose when it meets all functional and end-user requirements from the analysis stage

• Evaluation requires checking the actual output against the expected output or design requirements

• A solution that gives the wrong output is not fit for purpose even if the rest of the implementation is correct

• Database evaluation must include checking the accuracy of SQL output

• Any unmet requirement means the solution must be refined or corrected

Efficient use of coding constructs

• Efficiency refers to solving the problem without unnecessary repetition or wasted computation

• Fixed or conditional loops should be used instead of repeating blocks of code

• Arrays should be used instead of declaring multiple variables for similar data

• Nested IF or ELSEIF constructs should be used to reduce the number of comparisons

• Efficient code improves performance and reduces maintenance effort

Inefficient version

• This repeats the same code unnecessarily instead of using a loop

SET total TO 0

RECEIVE num1 FROM KEYBOARD
SET total TO total + num1

RECEIVE num2 FROM KEYBOARD
SET total TO total + num2

RECEIVE num3 FROM KEYBOARD
SET total TO total + num3

RECEIVE num4 FROM KEYBOARD
SET total TO total + num4

• This is inefficient as:

  • The same instructions are repeated four times

  • The number of inputs cannot be changed easily

  • The structure makes the program longer and harder to maintain

Efficient version

• This uses a fixed loop and an array to remove repetition

DECLARE nums[4]
SET total TO 0

FOR index FROM 0 TO 3 DO
    RECEIVE nums[index] FROM KEYBOARD
    SET total TO total + nums[index]
END FOR

• This is efficient as:

  • A fixed loop removes repeated code

  • The number of inputs can be changed by adjusting the array size and loop range

  • The program is shorter, clearer and easier to maintain

Robustness

• Robustness refers to the ability of the solution to handle unexpected or incorrect input without crashing

• Robustness is achieved through appropriate input validation at every required point

• Validation prevents invalid data from being processed and protects the program from runtime errors

• Robust solutions continue running safely even when users enter incorrect or unreasonable data

Non-robust version

• This version accepts invalid data and can break the program.

RECEIVE age FROM KEYBOARD
SET ticketPrice TO 10

IF age < 16 THEN
    SET ticketPrice TO 6
END IF

SEND ticketPrice TO DISPLAY

• This is not robust as:

  • The program accepts anything the user types

  • A negative age or a text input like "abc" will cause errors

  • The program can crash or give incorrect results

Robust version

• This version forces the user to enter a sensible age before the program continues

REPEAT
    RECEIVE age FROM KEYBOARD
UNTIL age >= 0 AND age <= 120

SET ticketPrice TO 10

IF age < 16 THEN
    SET ticketPrice TO 6
END IF

SEND ticketPrice TO DISPLAY

• This is robust as:

  • The conditional loop prevents invalid ages from being accepted

  • The program only continues when the input is sensible

  • Validation protects the program from crashes and incorrect outputs

  • The solution handles user mistakes safely