Developing customized visualizations

Merging multiple datasets in Tableau:

In this section, we will learn how to combine multiple datasets into one. Key point here is that to identify the column that connect two or more datasets together. Besides GHGRP dataset, you need to download ORIS dataset located here: https://bit.ly/2DCQZL8 and power generation dataset located here: https://bit.ly/3jVeizd. First, we will load GHGRP_data_2014_8_13_16.csv into the Tableau and then choose ghgrp_oris_power_plant_crosswalk_8_13_16.csv connect to it by using Facility Name columns that matches the facility name across two datasets. Finally, you need to choose powerplant generation num.csv file and connect it to ghgrp_oris_power_plant_crosswalk_8_13_16.csv by matching Oris Code and Plant Id columns:

Calculated fields:

Calculated fields help to create customized formula or combine several variables together to create a more insightful parameter for visualization. For example here we want to create two calculated fields as Emission Intensity which is defined as reported CO2 emissions over net generation of power plants and Efficiency Field defined as net generation over electric fuel consumption. These are defined as:

  • Emission Intensity: [reported CO2e emissions]/[Net Generation (Megawatthours)]

  • Efficiency Field: ([Net Generation (Megawatthours)]*3.412)/[Elec Fuel Consumption MMBtu]

In order to create calculated fields you need to go Analysis ---> Create Calculated Field:

Now use these two formulas to create these two calculated fields:

Now put Efficiency into the Columns and Emission Intensity into the Rows and put Plant Name and AER Fuel Type into the Marks and Efficiency and AER Fuel Type into the Filters. In the Mark, put AER Fuel Type to Color. In the Filter, click on Efficiency and choose filtering based on All Values:

Finally click on AER Fuel Type in Filter and choose COL and NG which shows coal and natural gas respectively:

As a result, the final visualization that shows the correlation of efficiency versus emission intensity for two fuel types of natural gas and coal is shown here by limiting the y-axis range from 0 to 3:

Statistical analysis:

In order to show trend lines, Tableau could fit a line to the data points that shows in average how data point are correlated to each other. In this section put Net Generation into the Columns and reported CO2e emissions into the Rows and change the measure into the average. Also put the Plant Name into the Marks. Now put the AER Fuel Types into the Marks and Filter and filter the fuel type similar to the previous section to coal (COL) and natural gas (NG). Finally, you should see this scatter plot:

Now add the trend line by going to Analysis ---> Trend Lines ---> Show Trend Lines:

Finally the analyzed scatter plot that shows the correlation of net generation versus CO2 emissions is shown here: