Three checks, one afternoon
You have one afternoon to make sure a report is safe to use. You could check the author, cross-check the figures, or test the sample for fairness.
You cannot do everything. Which action gives the most for your time? You must compare, choose, and explain why.
Key words
| Word | What it means |
|---|---|
| Reliable | gives the same result each time, so it can be depended on |
| Valid | measures what it says it measures |
| Corroborated | backed up by another independent source |
| Representative | a fair picture of the whole group it claims to describe |
| Bias | an unfair lean towards one side |
| Rationalise | give clear reasons for a choice |
| Recommend | say which choice is best, and why |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can compare actions that keep sources reliable and valid, and recommend one with clear reasons.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Six actions and what they catch
| Action | Effort | Catches | Misses |
|---|---|---|---|
| Check the author | Low | Unknown or unqualified writers | A good author who is wrong or biased |
| Check date and version | Low | Outdated figures | A new page that is wrong |
| Check citations | Medium | Claims with no evidence | Real citations that were misread |
| Cross-reference | Medium | A single wrong source | Sources that all copy one origin |
| Test the sample | High | Unfair or one-sided data | Faults outside the sample |
| Filter malicious data | High | Fake or planted records | Clever fakes that look normal |
The cells students fill in are left blank in this preview.
Apply the factors, then compare outcomes
Run each action on each source. Mark each check as pass or fail. Then compare what each action found.
An action that finds many faults is worth more than one that finds none. An action that takes a day and finds nothing is poor value for this job.
Worked example: outcomes for three sources
| Check | Source A | Source B | Source C |
|---|---|---|---|
| Author credible | Pass | Pass | Fail |
| Date and version current | Pass | Fail | Pass |
| Citations shown | Pass | Pass | Fail |
| Corroborated | Pass | Fail | Fail |
| Sample representative | Pass | Pass | Fail |
| Passes | 5 | 3 | 1 |
The cells students fill in are left blank in this preview.
Run it: which source passes most checks?
names = ["A", "B", "C"]
passes = [5, 3, 1]
best = 0
for place in range(len(names)):
if passes[place] > passes[best]:
best = place
print("Best source:", names[best])