A farmer believes that fertilizer runoff from a farm is killing the fish in a nearby pond. The farmer measures the amount of fertilizer in the pond each week and counts the number of dead fish. The measurements indicate that, as the fertilizer concentration increases, the number of dead fish increases. What would be a valid conclusion from this investigation and how can the farmer arrive at the conclusion?
And your answer is?
Based on the investigation, a valid conclusion would be that there is a causal relationship between the fertilizer runoff and the death of fish in the nearby pond. To arrive at this conclusion, the farmer must follow these steps:
1. Gather data: The farmer needs to collect measurements of the fertilizer concentration in the pond and the corresponding number of dead fish each week. This data helps establish a relationship between the two variables.
2. Analyze the data: After gathering the data, the farmer should plot it on a graph to visually examine the relationship between fertilizer concentration and fish mortality. The farmer should be able to observe trends, such as an increase in the number of dead fish as the fertilizer concentration rises.
3. Calculate correlations: To quantify the relationship, the farmer can calculate the correlation coefficient between the fertilizer concentration and fish mortality. A positive correlation would indicate that as the fertilizer concentration increases, the number of dead fish also increases.
4. Consider other factors: While the data suggests a relationship between fertilizer runoff and fish mortality, the farmer should also consider other factors that could affect fish deaths, such as temperature, oxygen levels in the pond, or the presence of other pollutants. Controlling for these variables is crucial to ensure that the observed correlation is indeed due to the fertilizer runoff.
5. Conduct additional experiments: In order to establish a stronger causal relationship, the farmer can consider conducting controlled experiments. For example, the farmer could set up separate ponds—one with fertilizer runoff and one without—and compare fish mortality rates between them. This type of experimental design allows the farmer to isolate the impact of fertilizer runoff on fish health.
By following these steps and considering other factors, the farmer can arrive at the conclusion that the fertilizer runoff from the farm is indeed responsible for the increased fish mortality in the nearby pond.