Tram Street: Designing a Defensible Internal Assessment
A student is completing the IB Geography internal assessment on how a new tram line has changed the retail environment along a 1.2 km street. The street has 84 ground-floor units, a mix of convenience stores, cafes, vacant units and a weekly market. The student has three days of fieldwork, one clipboard, a phone with a GPS app, and access to the school's 20-year-old land-use map. The tram opened two years ago. The student plans to record land use for every unit on one Saturday morning and to interview five shoppers chosen at random near the tram stop. The teacher warns that the assessment must show a clear geographical concept, a justified sampling strategy and awareness of limitations. The student wants to compare 'before' and 'after' but has no historical vacancy data.
1. Justify a sampling strategy for the land-use survey and explain how it would improve the reliability of the student's conclusion. [8]
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Population: 84 ground-floor units is small enough for a census, which is more reliable than a sample. Strategy: walk the full 1.2 km and record every unit using a consistent classification: convenience, cafe/food, comparison, services, vacant, market. Record opening hours, chain/independent, and whether the unit appears recently refurbished. Repeat on a weekday and a Saturday to capture temporal variation. Why reliable: full coverage avoids sampling bias; a fixed route and classification allow replication; GPS points allow mapping. Limitations: one student may introduce observer bias; a single Saturday may miss market days or seasonal vacancies. The conclusion should be based on the census plus a repeat survey, not on five interviews.
2. Evaluate the strengths and limitations of the student's proposed shopper interviews for investigating the impact of the tram. [6]
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Strengths: interviews can capture shoppers' perceptions, travel mode, frequency and spending, which land-use data cannot. Near the tram stop, they can show whether users are local or incoming. Limitations: five shoppers is a tiny sample with no sampling frame; choosing 'at random near the stop' over-represents tram users and misses car users and non-shoppers. Saturday morning may over-represent leisure shoppers. Closed questions may force answers; interviewer position and safety affect who agrees. Improvement: use a quota sample by age and mode, a short structured questionnaire, and a pedestrian count at fixed points. Link interview data to the research question rather than treating it as representative. Conclusion: interviews are useful as complementary qualitative evidence, not as proof of the tram's impact.
3. Recommend how the student should reframe the investigation to make a defensible IA given the available data. [10]
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Reframe from a causal 'before and after' study to a cross-sectional comparison of retail change and vacancy along the tram corridor, using the land-use map as a cautious baseline. Research question: 'How does retail composition and vacancy vary with distance from the new tram stop?' Method: census of 84 units; classify land use; calculate vacancy rate, diversity index and chain-store proportion by distance band (0-200 m, 200-400 m, etc.). Add pedestrian counts at three times and a short shopper questionnaire. Control: compare with a similar street without a tram, if time allows, or use the old map to identify change but state its limitations. Concept: regeneration, accessibility, gentrification or retail change. Conclusion: the IA can be defensible if it avoids claiming causation without baseline data and explicitly discusses sampling, reliability and bias. This is a stronger geographical investigation than an unsupported 'tram caused change' claim.