The Composting Op-Ed
A local newspaper publishes an op-ed arguing that the city's new curbside composting program 'pays for itself' and that 'residents overwhelmingly support it.' The program costs $4.2 million per year. It diverts 22,000 tons of food scraps from the landfill, where the tipping fee is $68 per ton. The city sells finished compost for $18 per ton and estimates that 85% of collected scraps become finished compost. The op-ed cites an 18-month pilot in two of the city's 40 neighborhoods, where 61% of households participated. It also cites a citywide online survey with 2,300 responses from a city of 180,000 residents; 74% of respondents said they supported the program. The op-ed does not mention that the pilot neighborhoods received extra outreach workers, that the online survey was promoted by an environmental advocacy group, or that the city must buy $600,000 worth of new collection bins in the first year. A city council member asks whether the op-ed's two claims are supported and what data would settle the question.
1. Test the claim that the program 'pays for itself.' Using the figures provided, calculate the annual landfill savings and compost revenue, then compare with the program cost. What important costs or benefits are missing?
Read the worked answer
Landfill savings = 22,000 tons × $68/ton = $1,496,000 per year. Finished compost = 22,000 × 0.85 = 18,700 tons. Compost revenue = 18,700 × $18 = $336,600. Combined = $1,832,600.
Annual program cost is $4.2 million, so even before first-year bins the program has a shortfall of 4,200,000 − 1,832,600 = $2,367,400. With $600,000 in bins, first-year shortfall = $2,967,400. The claim that it 'pays for itself' is therefore not supported by the cited figures.
The calculation also omits costs-collection labor, trucks, processing, administration, contamination disposal-and omits monetized benefits such as avoided methane or landfill expansion. Those omissions could narrow or widen the gap, but they cannot make the claim proven without numbers.
2. Evaluate the survey and pilot evidence for the 'overwhelming support' claim. Identify at least two problems and explain how each weakens the inference.
Read the worked answer
The survey is weak evidence for 'overwhelming' citywide support. It is an online, self-selected survey: 2,300 responses from 180,000 residents is about 1.3%, and people who choose to respond may be more motivated or more supportive. Promotion by an environmental advocacy group likely selects supporters. The 74% figure describes respondents, not residents.
The pilot is also limited: it covers 2 of 40 neighborhoods, and those neighborhoods had extra outreach workers, which could raise participation. A 61% participation rate measures whether households put scraps out, not whether they approve or whether the program would work citywide without extra staff. The op-ed generalizes from atypical areas and an unrepresentative sample. It may be true that support exists, but 'overwhelming' is not established.
3. Recommend two specific data collection steps the council should take before deciding whether to expand. Explain what each would measure and why it matters.
Read the worked answer
Two useful steps:
Commission a random-sample survey of residents with a known sampling frame, neutral wording, and a reported response rate. This would measure support without self-selection and could be weighted to the city's demographics. It matters because the current 74% cannot be projected to 180,000 people.
Run a full-cost accounting and a controlled expansion pilot: track collection labor, processing, contamination rates, bin replacement, and revenue per ton in several neighborhoods, including some without extra outreach. Compare costs and diversion with a matched comparison area. This matters because the 'pays for itself' claim depends on net cost, and the current pilot cannot show whether results persist at scale. A cost per diverted ton would let the council compare composting with landfill disposal directly.