Site Channel width (m) Plastic items in 20 m reach A 4.8 7 B 3.6 11 C 2.1 19 D 1.5 25 The table below shows data collected by students from four sites in a ...
Question 1 Report
| Site | Channel width (m) | Plastic items in 20 m reach |
|---|---|---|
| A | 4.8 | 7 |
| B | 3.6 | 11 |
| C | 2.1 | 19 |
| D | 1.5 | 25 |
The table below shows data collected by students from four sites in a drainage basin in Jamaica. At each site, they measured the width of the channel and counted the number of pieces of visible plastic in a 20 metre reach. The sites were visited after three dry days. Students suggest that plastic may accumulate where the channel is narrow, but they understand that a single visit provides limited evidence. The results are being considered before planning a follow-up fieldwork enquiry.
| Site | Channel width (m) | Plastic items in 20 m reach |
|---|---|---|
| A | 4.8 | 7 |
| B | 3.6 | 11 |
| C | 2.1 | 19 |
| D | 1.5 | 25 |
(a) State the site with the greatest number of plastic items. [1]
(b) State the relationship shown by the data. [1]
Students and shopkeepers in a market town were asked about the effects of a new bypass. Fig. 1 shows the interview locations selected by the fieldwork team. They stopped people outside a supermarket, at the bus station and on the older high street. The same four short questions were read aloud to each participant. The class wants to present the findings in a study figure for the town council, but recognises that some people may have been in a hurry.
(a) State one advantage of using the same questions for every participant. [1]
(b) State one group of people who may be under-represented by the locations in Fig. 1. [1]
(c) Explain how the students could reduce bias in their questionnaire sample. [3]
Answer Details
Plastic and channel width
- (a) Site D has the greatest plastic count, with 25 items in the 20 m reach. [1]
- (b) The data show a negative relationship: as channel width decreases, the recorded number of plastic items increases. For example, the widest channel is 4.8 m and has 7 items, whereas the narrowest is 1.5 m and has 25 items. This is an observed pattern, not proof that narrowness alone causes plastic accumulation. [1]
Bypass questionnaire
- (a) Asking every participant the same questions standardises the survey, so answers can be compared fairly. [1]
- (b) People who do not visit the town centre may be under-represented. Drivers using the bypass and housebound residents would also be valid examples because they may not be encountered at the supermarket, bus station or high street. [1]
- (c) Bias occurs when the sample favours particular types of people. The students could:
- select people randomly, for example survey every fifth passer-by, rather than choosing only convenient participants; [1]
- survey at different times and on different days, so the sample is not limited to one pattern of shoppers or travellers; [1]
- use additional locations, such as residential areas or bypass service areas, to include people missed by central locations. [1]
Examination reminder: use the data to state a relationship, but avoid claiming causation unless the enquiry has tested and controlled other possible influences.
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