Overview

Air quality monitoring is essential for evaluating environmental conditions and protecting public health.
This analysis compares nitrogen dioxide (NO₂) concentrations recorded at the Regina monitoring station with measurements from the National Air Pollution Surveillance (NAPS) network.

The objective is to determine whether the two monitoring systems demonstrate sufficient agreement to be considered comparable.

Load Libraries

Import and Prepare Data

Monitor Agreement

A scatter plot was generated to evaluate the relationship between the two monitors.
Points clustering near the 1:1 line indicate strong agreement.

Statistical Evaluation

Key statistical metrics were calculated to quantify monitor agreement.

Metric Value
Correlation 0.459
Bias 0.004
RMSE 8.115
Nash–Sutcliffe Efficiency -0.071

Regression Analysis

Linear regression was used to further assess the strength of the relationship between measurements.

## 
## Call:
## lm(formula = Regina ~ NAPS, data = paired)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -45.956  -4.124  -1.605   2.510 107.967 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 5.577342   0.025704   217.0   <2e-16 ***
## NAPS        0.454676   0.001995   227.9   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 6.897 on 194314 degrees of freedom
## Multiple R-squared:  0.2109, Adjusted R-squared:  0.2109 
## F-statistic: 5.192e+04 on 1 and 194314 DF,  p-value: < 2.2e-16

Bland–Altman Agreement Analysis

The Bland–Altman plot provides insight into measurement bias and limits of agreement between monitors.

Summary

This analysis evaluated agreement between the Regina and NAPS monitoring stations using graphical and statistical techniques.
Correlation, bias, RMSE, regression, and Bland–Altman analysis collectively provide a comprehensive assessment of monitor comparability.