# Scatter Plot

**Site Name**

Select a site by clicking on it. This tool has been restricted to plotting one site at a time.

**Variables**

Select a variable by clicking on it. The pollutants available will depend on the selections of other parameters (e.g. site and date range selected). This tool is limited to plotting up to 2 variables together. To choose each variable, first select one then hold the CTRL key while selecting the other.

**X Axis Variable**

Choose which variable will be associated with the x axis.

**Y Axis Variable**

Choose which variable will be associated with the y axis.

**Date Range**

Choose to enter either 'Specific Dates' or 'Specific Years'. 'Specific Dates' allow you to choose day, month and year to start and stop your analysis. 'Specific Years' will allow you to quickly choose the years of interest to you and the analysis will commence on 1st January and run until 31st December of those selected years.

01/08/2007 - 29/07/2021

**Type**

Use this drop-down menu to select the way you want your data split. The default option will produce a single plot covering the entire range of the data. Selecting 'Weekday' will produce an individual plot for each day of the week and so is helpful in highlighting differences throughout the working week and weekends. Selecting 'Month' will show twelve plots, one for each month, helping to visualise seasonal changes through the year. Selecting 'Season' will split the data into proper seasons showing any variation between seasons. Selecting 'Wind Direction' will split into eight compass point sectors, and selecting 'Wind Speed' will split into four quartiles using the modelled wind direction or speed from the UK air quality forecast which can be useful in identifying particular sources.

**Method**

Choose the method for producing the scatter plot. 'Scatter' will produce a standard scatter plot where each corresponding x and y combination is presented using a point on the plot. 'Hexbin' is useful when the dataset is large; in the plot data is binned into hexagonal cells and the colour scale represents the count of data points within the bin. 'Density' produces a smooth 2 dimensional representation of the relationship between the x and y variables, calculated using a kernel density estimate approach.

**Fit Linear Trend**

Select to add a linear model fit to the scatter plot with the equation of the line and the R^{2} value. Only available when the 'Scatter' method is chosen.

**Fit Smooth Line**

Select to add a smooth fit to the underlying data with estimated 95% confidence intervals (grey shading); the smoothed fit can be extremely useful to evaluate if the relationship between variables is non-linear. Only available when the 'Scatter' method is chosen.

**Colours**

Select from a variety of set colour templates. Only available when the 'Hexbin' or 'Density' methods are chosen.