6.7 Quick review questions

The Giant Mine in Yellowknife, Canada, ceased operation in 1999 after operating for 50 years, during which 237,000 tonnes of arsenic trioxide was released.

One study (Houben et al. 2016) examined the arsenic concentration in lake water from 25 lakes within a 25km radius of the mine (11 years after the mine closed), to determine if the arsenic concentration was related to the distance of the lake from the mine.

They also recorded the type of bedrock (volcanic; sedimentary; grandiorite), the ecology type (lowland; upland), the elevation of the lake (in metres), the lake area (in hectares), and the catchment area (in hectares).

  1. What is the response variable?
  2. What is the explanatory variable?
  3. Is the variable “Catchment area” likely to be a lurking variable?
  4. Is the variable “Type of bedrock” likely to be a confounding variable?
  5. What is the best description of the variable “Ecology type?”
  6. What type of study is this?


Houben AJ, D’Onofrio R, Kokelj SV, Blais JM. Factors affecting elevated arsenic and methyl mercury concentrations in small shield lakes surrounding gold mines near the Yellowknife, NT, (Canada) region. PloS one. Public Library of Science San Francisco, CA USA; 2016;11(4):e0150960.