# finding the correlation between population density in a city and the city's PM 25 value

I am a high school student doing a report for my environmental science course, IB diploma.

My question is about how to find the correlation between two data sets.

My question of interest is whether a city's population density affects the city's air quality, measured in PM 25.

Though I have the research question, I don't really know how to approach it. I am not familiar with statistic analysis and don't know which tool and how I would use to try to answer my question in mind.

I plan to choose around 10 cities and gather the two values for each city from a particular year, from there I guess I can do a graph with the independent value (population density) on x-axis and dependent (air quality measured by PM 25) on the y-axis. Please help me and guide me how I would do from there and whether my choice of the range of data is wise, if not, how can I do?

Thanks a lot!

• The data may not lie on an approximate straight line, in which case a single correlation value might be misleading. Before deciding on how to model the data, visually inspect a scatterplot of all data points to determine if a straight line roughly models the relationship sufficiently that it would be close to what is shown on the scatterplot. A simple correlation value might indeed give a good understanding of the relationship, but I advise you to plot first. BTW, I also went to an advanced academic high school and will be glad to help in the project - as will many people you find here. – James Phillips Aug 12 at 16:00