Check for Errors: Speed and Accuracy in Comparing Coded Data
What the section asks
Check for Errors gives you pairs of strings - number codes, letter codes, ZIP codes, street addresses, routing labels - and you decide whether the two entries are identical or different. It is timed and fast-moving, with many short items. Your score reflects both how many you complete and how many you get right, so a careless error costs more than a slow item.
Concepts to master
- Systematic comparison. Read the first string, then verify the second left to right in the same order every time.
- Chunking. Break long strings into groups of three or four characters and compare group by group.
- Transposition. The most common planted error is two characters swapped: 7801 versus 7081, AB versus BA.
- Similar glyphs. 0/O, 1/I/l, 5/S, 8/B, 2/Z, 6/G are deliberately confusing.
- Inserted, dropped, or shifted characters. A missing hyphen, an extra digit, a leading zero, or a reordered word in an address all make the pair different.
- Pacing. Answer decisively; do not re-litigate a completed item.
Traps
- Assuming a near-miss is the same because the beginning and end match; the error usually hides in the middle chunk.
- Spending too long on one long string and running out of time.
- Changing an answer on a vague hunch rather than a specific mismatch you can point to.
- Skimming digits because the font is small; read every character, not the shape of the word.
- Letting speed pressure turn a genuine difference into "same."
Rule of thumb
Compare chunk by chunk and stop at the first mismatch - if you find one, mark different and move on. If every chunk matches through the final character, mark same without second-guessing.
Worked example
List A: ZQ 4-7801-KL. List B: ZQ 4-7081-KL. Chunk one (ZQ 4-) matches; chunk two is 7801 versus 7081 - the 8 and 0 are transposed. Mark different. If chunk two had read 7801 as well, you would check -KL and then mark same.