Jump to main content.


Tutorial 1

Evaluating National-Level Risk-Related Impacts

An important use of the RSEI model is to identify areas that have potentially high risk-related impacts. This exercise will walk you through several different ways of doing this. First, you will perform a national-level selection for the year 2002. You will look at the results by media and state, and examine the data using several different preformatted functions included in the RSEI model.

Step 1.1 Perform a National-Level Selection

The first step in any analysis using the RSEI model is to determine the set of elements you wish to select. This is done by performing a selection. Open up the model to display the Welcome to RSEI screen. Click on the Select button at the top left of the menu panel. This brings up the Select elements... screen. Here, you can select elements based on any variables included in the model, including chemical characteristics, geographic location of the facility, year, and many more. You do this by creating a set of selection statements. For this exercise, we will create a very simple selection statement.

For each exposure pathway from each chemical release, the model generates an 'Indicator Element.' For instance, a release of the chemical benzene to air via a stack from the 'ABC' Facility in 1999 is an 'Indicator Element.'

Note that if you have done any selections since installing the RSEI model, your last selection statement will appear on the Select elements... screen. To remove it, simply click on the Clear button. You will see a line of text on the screen, 'Choose records where all of the following apply'. This is a bracket statement that tells the model what to do with the information that comes next. You can change the bracket statement from 'all' to 'any', 'none', or 'not all' by clicking on the 'all' and selecting an option from the drop down menu. But for now let it remain 'all'. Click on the circle to the left of the text, and select 'Add condition'.

Selection statements tell the model what releases you wish to select.  Selection statements are comprised of bracket statements that tell the model to select records where all, any, none, or not all of the conditions apply and condition statements, that specify exactly what your conditions are.

The condition statement contains the criteria you use to select your releases.

You will see the following text line:

1. Chemical Flags.Year Chemical Added is equal to      

Click on the first part of the text line, and a drop-down menu will appear. This menu contains all of the variables contained in the model that you can use in your selection statements. They are grouped according to the type of variable. Click on the group 'Submission'. To the right you will see another menu with all of the variables in this group. Click on 'Year'.

The text line will change to 1. Submission.Year is equal to      . Click on the blank at the end of the line, and select '2002' from the list.

RSEI model screenshot, 'Select elements...' showing the selection statement 'Choose records where all of the following apply: Selection Year is equal to 2002.'

This will now select all TRI-reported releases that occurred in 2002. Click somewhere in the window outside of the box you just typed in, so that the entire text line is blue (this enters your change). Click on the Submit button at the top of the Select elements... screen to submit the selection. The model may take a few minutes to complete the task.

If you accidentally submit an incomplete or inaccurate selection statement, you cannot stop the submission or go back to the statement until the model has processed your submission completely. Once the model is done, click on the Select button again to reopen the Select Elements... screen, correct the selection statement, and resubmit it.

When the model is done with the selection, the Select elements... screen will disappear. The number of facilities, chemical releases, and elements that are selected in your set will be displayed in the top right corner of the screen.

Now that you have your selected set of scores, you can analyze them in different ways. To get a quick summary of the differences in risk-related impacts between states, click on Thematic Maps at the top of the screen.

The model will display a US map with variations in color representing differing levels in impacts. Your map may show Alaska and Hawaii; if you want to see only the continental US, click and drag the map to the left until Hawaii and Alaska no longer show. The legend at the left side of the screen shows what colors on the map correspond to what values. The map will currently show all gray because the map is set to 2006 as the default year. To switch to 2002, select from the drop-down menu next to Select Year. Also make sure that the Theme box shows 'Score." If you want to increase the size of the map, draw the outline of a box around the area you want to enlarge with the cursor while holding down the right mouse button. To outline the states, click on the 'Show feature outlines' box.

RSEI model screenshot, 'Thematic Map of All 2002 Scores,' showing a US map where gradations of color from green to blue represent differences in risk-related score.
Thematic Map of All 2002 Scores

Step 1.2 Results by State

To get a more detailed look at 2002 scores, you can break down your national-level selection by state. Click on the Custom Tables button at the end of the second row of menu buttons at the top of the screen, and the screen shown below will appear.

RSEI model screenshot 'Custom Tables' view showing the screen before a table is loaded or created, with an empty bottom screen and the RSEI menu buttons across the top of the screen.

In this screen you can create and customize crosstab tables, based on any combination of variables you choose. To create a new crosstab table, click on the New Table button. The Select Dimensions screen will appear. This screen lists all the variables included in the RSEI model. The variables are listed in the form Data table.variable name, where the data table is similar to the variable group used in the Select elements... screen. A complete listing of all variables is provided in Chapter 5 of the User's Manual.

Select the rows and columns that you want to appear in the crosstab table. You may select any number of variables, but selecting more than two or three will greatly increase the time needed to generate the table and the complexity of reading the table. Note that the various RSEI outputs (e.g. pounds, hazard score, risk-related score, etc.) will be the contents of the cells of the crosstab. You do not need to specify RSEI outputs at this point.

RSEI model screenshot 'Select Dimensions' showing all of the possible dimensions that can be used to create a custom table.  'Facility.State' and 'Release.MediaText' are checked, and the name '2002 State by Media' is entered at the bottom.

We want to look at state-level results, so select 'Facility.State'. It is often informative to break down results by media, in order to assess what exposure routes are associated with the highest risk-related impacts. So select 'Release.Media Text', which will provide the text description of the medium into which each chemical is released. In the box to the right of 'Name' at the bottom of the screen, type in a name for this table you are creating, such as '2002 State by Media'. All of the tables you create in the RSEI model are saved on your hard drive in the C:\Program Files\RSEI\User directory for later use. Hit Run! and the model will create your crosstab table. It may take a few minutes to generate. When the model is finished, you will see the new crosstab table, as shown below.

RSEI model screenshot 'Crosstab Table, State by Media' showing a custom table with State as the column variable and Media Text as the row variable.  The 'Value Selected' above the table is 'Risk-related Results.'
Crosstab Table, State by Media

This table shows, for each state, the risk-related score for each medium. This is the top number, in black, in each cell. For cells with non-zero values, the number in red beneath the score is the cell's percentage of the total score of all the cells in the table (the total can be found in the lower right corner). The values below the top number in black in each cell can be changed by clicking Options, then Cell Display. The default (the value in red) is the 'Total Pct'. To turn it off, simply click on the text so that the check mark is removed.

The box at the top of the screen, where 'Risk-related Results' is displayed, controls what numbers are shown in black in the cells of the table. Explanations for each type of number can be found at the end of Chapter 9 in the User's Manual. 'Risk-related Results' refers to the score: the risk-related, unitless number that takes into account the chemical release, its toxicity, environmental fate and transport, exposure assumptions, and the number of exposed people.

Note that there are many media that have only zeros for entries. To get rid of all entries that have no nonzero values, click on the minus sign to the left of the row header 'Media Text'. This collapses the rows, and the minus sign is replaced with a plus sign. Click on the plus sign to expand the row again; now, however, the zero-only rows will not be displayed.

RSEI model screenshot 'Crosstab Table, Zero-Only Rows Removed' showing a custom table with State as the column variable and Media Text as the row variable.  The 'Value Selected' above the table is 'Risk-related Results.' Table cells with '0' are not showing.
Crosstab Table, Zero-Only Rows Removed

Any time you change the 'Value Selected', you should collapse and expand the rows and columns to refresh the table. Otherwise, rows or columns that were not shown originally because all of the values were zero may not show when the summary is changed, even if in the new summary their values are non-zero.

Because the crosstab table displays so much information at one time, sometimes it is useful to quickly summarize the information in the table. The Sorted Table function works off the crosstab table's current display and shows each cell in descending order. Click on the Sorted Table button and the screen shown below will appear.

RSEI model screenshot 'Sorted Table, State by Media' showing custom table '2002 State by Media' in form of a sorted table with columns Rank, State, Media Text, Value, Percent, Cumulative Value, and Cumulative Percent.
Sorted Table, State by Media

This table shows each state-medium combination, listed in descending order of risk-related impact. The sixth column, 'Cumulative Value', shows the total value of the score for each entry and all of those above it. The 'Cumulative Percent' column functions in a similar way. You can see that direct water releases in Pennsylvania account for almost 12 percent of the total risk-related impact in the country.

To do a more direct comparison of states, go back to the custom table by clicking on the Table button. Collapse the rows by clicking on the minus sign to the left of the 'Media Text' row header. Then click on the Sorted Table button again. This time, instead of showing state-media combinations, the table only shows the state rankings. You can see that Pennsylvania is the state with the highest calculated risk-related impact, accounting for more than 18 percent of the nation's total.

RSEI model screenshot 'Sorted Table, by State Only' showing custom table '2002 State by Media' in form of a sorted table with columns Rank, State, Value, Percent, Cumulative Value, and Cumulative Percent.
Sorted Table, by State Only

You can also look at the results graphically. Click on the Graph button above the table, and the following screen will appear:

RSEI model screenshot 'Custom Graph, Total for All Media for All States' showing custom table '2002 State by Media' in form of a graph with 'State' along the horizontal axis and 'Risk-related Results' along the vertical axis.
Custom Graph, Total for All Media for All States

This graph is hard to interpret, due to the number of states shown. To limit the number of states, perhaps to just those in the top five of the sorted table, click the Filter button at the top of the screen, and the Set Filter screen will appear.

RSEI model screenshot 'Set Filter' dialog showing 'MediaText' and 'State' in the top box as variables to filter with highlighted values for State showing in the lower box. Boxes for 'OH' 'PA' and 'TX' are checked.

Click on State, then click on the boxes next to the top five states: PA, CA, TX, OH, and IL. Click Apply Filters and the graph will then display only those states with checked boxes, resulting in a more easily intelligible graph.

RSEI model screenshot 'Custom Graph, Total for Top 5 States by Risk-Related Results' showing custom table '2002 State by Media' in form of a graph with 'State' along the horizontal axis and 'Risk-related Results' along the vertical axis.  Only five states (CA, IL, OH, PA, TX) are showing on graph.
Custom Graph, Total for Top 5 States by Risk-Related Results

This tutorial began with a national-level analysis, then narrowed in on the five states with the highest risk-related results. The next tutorial will narrow the analysis even further, looking more closely at one state.

Top of page


Local Navigation


Jump to main content.