Sampling, Survey Bias, Qualitative Mapping & Exam Techniques

Convenience sampling
- Definition: Select the first set of respondents you encounter with no prior filtering.
- Example: “Take the first $50$ people that pass by and ask them to fill in the survey.”
Quota sampling
- Adds one extra layer of filtering before using convenience.
- You first identify all potential respondents meeting a criterion (e.g. “people who live in Tampines” or “only girls”).
- From that filtered pool you then take the first $50$ who walk past.
- Hence: convenience within a pre-specified subgroup = quota.
Practical rule: “Any extra filter → quota; no filter → convenience.”
Simple random vs. stratified random
- Both insist on genuine randomness rather than convenience.
- Typical university study sequence:
1. Obtain a full list of, say, $200$ willing participants.
2. Either pick a simple random sample (every name has equal chance) or a stratified sample (split the $200$ into meaningful sub-groups, then randomly pick proportionally).
- This extra organisational work distinguishes them from convenience/quota.

Reliability problem illustrated by the “MRT exit” example:
- Asking “Which neighbourhood facilities do you use?” right outside an MRT station guarantees almost $100\%$ MRT usage responses → sample is biased.
- Remedy: conduct the same question across multiple sites or intentionally remove the MRT as a counted facility.
Marking advice:
- Examiners reward answers that identify the bias and explain why it skews the results.
- Where space is provided in the exam booklet, use it—markers expect elaboration (examples, numerical illustrations, corrective suggestions).

“Mental map” questions
- Two sketches (e.g. a local worker vs. a tourist around KLCC) can be contrasted for clusters, emphases, or missing details.
- Infinite variation ⇒ focus on broad principles, not rote memorisation.
“Repetition” cue: look for repeated symbols or shapes.
- Example: student draws all houses as squares → comment that their mental image standardises housing forms.
Low exam weight: rarely appears (did not appear in last year’s N-Level paper), so study lightly.

Fire-safety programme details that score marks when elaborated:
- Teaches residents to call $995$ during a fire.
- Encourages use of the “MyResponder” app, which alerts SCDF and nearby trained volunteers.
When a question offers $2$ – $3$ marks, expand with how and why each initiative builds community resilience (e.g. faster response times, neighbourhood empowerment).

Question type: “Compare the changes in the share of deaths between China and India.”
Scoring pattern:
- One sentence must show both countries for one interval.
- Repeat for the next interval.
Sample high-credit response:
- “Between $1990$ and $2015$ , China’s proportion of deaths doubled from $6.0\%$ to $12.3\%$ while India’s rose from $4.0\%$ to $10.5\%$ .”
- “From $2015$ to $2019$ , China’s share fell slightly to $12.8\%$ whereas India’s continued to climb.”
Key comparison vocabulary: while, whereas, compared to, in contrast to.
Avoid mere listing with “and”; it does not signal a difference.

High-scoring essays adopt a clear, strong stance (“agree” or “disagree”) rather than a vague “to a greater extent”.
Typical upper-secondary template (for SAC/‘Fi’ or N-Level): three-paragraph evaluation:
1. Introduction & claim.
2. Main argument with evidence and example.
3. Counter-argument or limitation + conclusion.
Developing an example
- State example first, then explain its relevance.
- E.g. “HD memory posts about East Coast Parkway picnics allow Singaporeans to archive shared experiences, reinforcing place attachment.”
- Link explicitly: “This demonstrates how digital media preserves collective memory rather than individual nostalgia.”
Examiner’s view: If you genuinely know a valid example, you probably understand the concept—nevertheless, a lone example with no explanation often caps at $1$ mark.

Direct impacts: immediate physical consequences (e.g. sea-level rise flooding coastal homes).
Indirect impacts: longer-term or mediated (e.g. economic disruption leading to migration).
Comparative point often framed through time-scale:
- Indirect effects may seem distant (“ $50$ years away”) but can manifest sooner (“struck $20$ years $\,$ earlier than expected”).

Use comparison words whenever the prompt says “compare” or “differences”.
Elaborate each listed point: definition → explanation → example.
Numerical data: always include both the initial and final values, plus the direction of change.
When space is abundant on the paper, markers expect fuller development; when space is tight, prioritise clarity and directness.