Frequently Asked
Questions
Tools and Functions
Using the map and data
Computer/connection
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How do I use the map tools?
The
tools on the left hand side of the map provide familiar
functions like panning, zooming in and out, but they
also help the user with more in depth functions, like
retrieving more information about any point
on
the map ("Identify"), finding a location, or querying.
Click here for a guide to the tools and other elements
of the
map
page.
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I checked boxes next to layers
I wanted to display but I don't see them.
Another layer may be obscuring the display. Try unchecking
the layer above. Also, if you have turned off the Auto
Refresh, you will need to click the Refresh Map button
to have the layers re-drawn. These options are located
below the Layers listings.
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How can I find detailed
information about an item on the map?
The identify function allows you to view the attributes of the highlighted,
or "active", layers at the location you clicked. First make sure
the Layers tab has been selected then highlight the layer you are interested
in (i.e., Land Use 1999 or Pesticide Sprayings 1956-1990.) Then select the
Identify button  in
that map. Click on the item you are interested in and the results will be returned
in the Map Information box.
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How can I save a map image?
Right click inside the map window and chose Save Image
As to save the contents of the map window.
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Why doesn't the Back button
work?
Using your browser's Back button when in the map viewer
will cause an error. This is a known bug! You can move
around between pages by using the Quickstart and Map tabs
at the top of the screen.
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What is a query and how do
I use the Query tool?
The query tool allows you to look for specific pieces
of information in a data layer. For example, you might
want to query the asthma hospitalizations layer for all
towns with greater than average hospitalizations. Once
you perform a query using the instructions below, the results
will be displayed in the Map Information box and the features
of the layer (in this example, towns) that met criteria
in the query will be highlighted.
1. Click on  .
2. Select the layer you would like to query, and make that layer active by
selecting the radio button next to the layer in the Layer list. It should look
like this:  .
3. In the Map Information tab, select the field you would
like to query in the drop-down list entitled Field.
4. Select the operator to use in your calculations in
the drop-down list entitled Operator. (Note: the default
is =, the equals sign).
5. Either click on Get Samples to retrieve your choices,
or type in what you want to query for. NOTE: It is recommended
that you click on Get Samples because the searches and
queries are case-sensitive.
6. Select the value you would like to query for in the
drop-down list entitled Sample Values.
7. Click on Add to Query String. Your query is added to
the text box.
8. If you would like to query for only one attribute,
then click on Execute.
9. If you would like to query for more than one attribute,
then click on And or Or.
NOTE: *And allows you to query for records that have both query arguments true.
*Or permits you to query for records that have either or
both query arguments true.
10. If you are querying for more than one attribute, repeat
steps 3 through 7.
11. Your results will appear in the same Map Information
tab.
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How can I see a full list of
included data?
Click here for a full list of the available data.
All data is included in the "Build Your Own Map" option
in the Get Started box.
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What is metadata?
Metadata is “data about the data.” Metadata
is all the information that will help you better understand
the data, and includes details about the quality, source,
and content of the data. The use of metadata is standard
in the GIS industry, and the methods for reporting metadata
used here are the standard developed by the Federal
Geographic Data Committee (FGDC) To access metadata,
click on the data layer you are interested in and the metadata
will open in a new window.
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The map displays the data
as a range. How can I get the actual numbers?
You can use the Identify tool and click on a specific town or other map item
to reveal detailed information.
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Why did you use these particular
data layers?
The primary objective of the pilot version of this application
was to make the Institute's original research on breast
cancer and the environment on Cape Cod publicly available.
The secondary objective was to enhance these data with
other publicly available environmental and public health
data sets for MA. The data included in this version of
the application are primarily publicly available data sets
from the Environmental Protection Agency (EPA), Massachusetts
Geographic Information System (MASS GIS), and the Massachusetts
Department of Public Health (DPH).
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What data did you want to
include that you couldn't?
The purpose of MassHEIS is to bring together geographic
data on health effects and environmental pollutants so
that potential relationships can be explored by researchers
and the public. In the context of this project, environmental
data are useful if they can be used to estimate pollutant
exposures or evaluate relationships between human activities
and environmental change (e.g., how does drinking water
quality relate to the land uses within drinking water well
recharge areas?). Health data are useful if they are systematically
collected, can be expressed with reference to an expected
frequency in the underlying population, and can be shared
on a scale that is relevant to variations in pollutant
exposures or demographic factors of interest. The data
currently included in MassHEIS are the most relevant we
were able to identify, but many of the included data sets
have limitations. Data on many environmental and health
features of interest are simply not available. For example,
only limited data are available on prevalence of learning
disabilities and autism; rates of many common cancers and
health effects would be more informative if mapped by census
tract rather than by town; and pollution monitoring data
are extremely scarce. With a greater state and federal
investment in public health tracking, more could be learned.
A few examples of data we were not able to obtain are
described below:
(1) Established risk factors for breast and other cancers, including body weight,
alcohol use, and tobacco use: These data are only available for major metropolitan
statistical areas in MA through the Behavioral Risk Factor Surveillance System
(BRFSS).
(2) Brownfields: A compilation of all brownfields in the state does not currently
exist. The MassDevelopment agency terms brownfields as "vacant, abandoned,
or underutilized industrial or commercial properties where expansion, redevelopment,
or improvement is complicated by real or perceived environmental contamination
and liability." MassHEIS does, however, display a data set, the MassDEP
Tier Classified Oil and/or Hazardous Material Sites, pinpointing all the sites
currently going through the Mass. 21E regulatory clean up process.
(3) Pesticide application: Silent Spring Institute compiled detailed historical
data on wide-area pesticide applications across Cape Cod from the 1940s to
1990. Comparable historical information for the rest of the state has not been
compiled, and no electronic, geographically-oriented data on current pesticide
applications are available in MA to map (although certain land use categories
may be assumed to involve pesticide use). Other states, such as California,
have pesticide application reporting requirements and tracking systems that,
if implemented in Massachusetts, would allow mapping of all pesticide applications
by registered applicators for the entire state.
(4) Current data on modeled hazardous air pollutants: The EPA published a national
hazardous air pollutant model using 1996 data, but has not published an updated
version. New data would allow trend analysis and comparisons with current patterns
of respiratory health effects.
(5) Cases of Asthma: The BRFSS collects self-reported data on cases of asthma
but these data are only available for limited geographical areas. Instead,
we chose to map incidence of asthma or asthma-related hospitalizations, because
these data are available by town for each town in MA.
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Why do you include only Massachusetts?
Prompted by the breast cancer incidence rates that are
20% higher on Cape Cod than the rest of MA, Silent Spring
Institute in 1994 began a long-term research program to
investigate the possible role environmental factors have
on breast cancer incidence on Cape Cod. Because Cape Cod
is a fragile ecosystem, with water resources easily affected
by contaminants deposited on the land surface or leached
from wastewater, breast cancer activists called for an
investigation of the role that environmental pollutants
played in the long-term health of Cape residents. As part
of that study, Silent Spring Institute created a Geographic
Information System (GIS). GIS is a computerized database
that can be used to store, analyze, and display data, particularly
data associated with locations on a map.
HEIS is intended to provide public access to the integrated health and environmental
information gathered during the course of the Cape Cod Breast Cancer and Environment
Study and thus most detailed data are available for Cape Cod. The secondary
objective was to enhance these data with other publicly available environmental
and public health data sets available for MA. The data included in this version
of the application are primarily publicly available data sets from the Environmental
Protection Agency (EPA), Massachusetts Geographic Information System (MASS
GIS), and the Massachusetts Department of Public Health (DPH).
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What is statistical significance
and why is it so important?
Statistical significance is a useful guideline in interpreting
research findings because it assesses the likelihood that
results are due to chance alone. Statistical significance
is based on a number called a "p-value." By convention,
results achieving a p-value less than 0.05 are called statistically
significant, which simply means that there is one chance
in 20 that the finding is due only to chance. The traditional
cutoff for statistical significance of p less than 0.05
is arbitrary, and an Standardized Incidence Ratio (SIR)
that approaches but does not attain statistical significance
may still be of interest.
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How accurate is the data?
Because the data come from a number of different sources,
the quality of the data can vary. Generally there are two
components to the quality of information in GIS. The first
is the accuracy of the geographic coordinates used to locate
information relative to its actual location . Second is
the accuracy of the attributes associated with the geographic
point. The first component is unique to GISs while the
second component would apply to any database. Different
sources have different quality control mechanisms. Most
of the data included in MASS HEIS comes from organizations
with established quality control procedures and it is important
to refer to the original source when evaluating data quality.
As a quality control measure, all Silent Spring Institute
data were verified by a staff member who did not participate
in the data entry. By clicking on the data layer you can
learn about the sources of other data sets included in
HEIS and can follow the links back to the original sources.
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What are SIRs and why are they used rather than
rates?
Standardized Incidence Ratio, or SIR, is a common tool
for monitoring disease rates. Incidence is the number of
newly diagnosed cases in a given location during a given
time period. An SIR compares the actual number of cases
for a given place and time to the number that would be
expected based on cancer rates in some comparison area.
SIRs are usually written as 100 or 125 instead of 1.00
or 1.25. An SIR of 100 means that the actual number of
cases equals the expected number. An SIR of 125 means that
the actual number of cases was 25% higher than expected.
An SIR of 75 means that the actual number of cases was
only 75% of the expected number. For more information,
see our glossary.
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What are limitations
of the data?
The quality of inferences that can be drawn from the data
depend on the quality of the original data. Information
in HEIS depends on varying sources of data, methods of
collecting and organizing data, scales of the data, and
completeness and accuracy of historical records. In addition,
Silent Spring Institute has followed standard practice
in not reporting cancer information where fewer than 5
cases appeared in a particular town or census tract in
a particular time period in order to protect the privacy
of individuals. We also only included data occurring with
a high enough frequency to be meaningful when mapped. For
example, Institute researchers determined that birth defects
are not prevalent enough to map at the municipal level,
given that such data have only been reported to the public
for three years. In the future, it may be possible to map
birth defects by town by aggregating data over a longer
time period. To learn more about any particular data layer,
click on the data layer.
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What does -999 mean?
Where data was not available or censored, the value -999
was substituted to clearly differentiate the record from
those with real data. Silent Spring Institute is invested
in protecting the privacy of individuals and has followed
standard practice in censoring town level cancer data rates
where fewer than five cases appeared in a particular time
period.
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Why is some data displayed
as points and some as shapes?
Data for an area (e.g., town, census tract, county, or
school district) are represented by a color shade for that
area. Data related to a specific location (e.g., a factory)
are represented as points. Most of the health data is represented
as shapes and most of the environment data as points. Although
the reported observation (e.g., cancer rate) for a municipality
appears evenly distributed throughout the town, it may
not be. Further, though much of the environmental data
are represented by a single point or location on the map,
that does not mean that the impact of the facility does
not reach further than its immediate location. To protect
privacy, health data that pinpoints individual cases is
generally not released. Instead, health data are aggregated
and displayed by census tract, block group, or town level.
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How can I find out where
the data came from, how it was collected, quality control
methods, and other information?
Metadata, "data about the data" is information
that will help you better understand the data, and includes
information about the quality, source, and content of the
data. The use of metadata is standard in the GIS industry,
and the methods for reporting metadata used here are the
standard developed by the Federal
Geographic Data Committee (FGDC) Most data sets include
links back to their originating sources. To access metadata,
click on the data layer you are interested in and the metadata
will open in a new window.
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Why do the time frames
for the data sets vary?
Time frames for data sets we included are typically limited
by the source of the data. For example, cancer rates are
not available prior to 1982, when the MA Cancer Registry
was initiated. In some cases, we were able to provide more
extensive historical environmental data for Cape Cod as
a result of the Institute's original research, but good
quality historical data are largely unavailable electronically
for the rest of the state.
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Why is it difficult to compare
data?
It can be difficult to compare data over time and over
geographic areas because of varying sources of data, methods
of collecting and organizing data, scales of the data,
and completeness of historical records. For example, different
sources of data you may see on the maps include: breast
cancer statistics for your town from the Massachusetts
Cancer Registry; pesticide spraying data compiled by Silent
Spring Institute researchers; and toxic release data supplied
from the EPA’s Toxic Release Inventory (TRI) index.
You can learn more about the datasets by clicking on the
data layers.
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How can I/should I interpret
what I see?
Very carefully. Maps are a powerful tool for conveying
information, but they can be easily misinterpreted. When
interpreting a map that you have created, be sure that
you look carefully at the legend to confirm the range of
values each color represents. When creating a map with
multiple layers, pay close attention to the time frames.
While they do not have to be concurrent, you should consider
their time frames in making inferences about relationships
between factors. In addition, be aware of how the different
data sets we have provided were generated. Some, like hazardous
air pollutants, are models, or projections. Others, such
as asthma, are indicators of a phenomenon (e.g., asthma-related
hospitalizations), rather than an absolute measure (e.g.,
people in the town with asthma). Use the metadata feature
to learn the source of the data you are mapping. Finally,
variation is expected due to chance. Look for indications
of statistical significance, consistent trends over time,
and large sample sizes to determine if a phenomenon is
significant. We have gone to great lengths to attain the
best possible data sets for this project, however, they
do not communicate seamlessly. To make accurate inferences
using this mapping tool will require awareness on your
part of the data sets with which you are working.
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Should I cite a map and how
should I do it?
We ask users of MASS HEIS to please cite the use of the
maps in your work. Citing data files and maps retrieved
from online sources is important for the following reasons:
• It is critical to acknowledge the authors and developers of a dataset,
whether published or unpublished;
• It is valuable for us, our funders, and our data sources to know that
the data and information we make available are useful to users;
• The inclusion of data citations is crucial to provide the relevant information
needed for users to confirm the accuracy and credibility of the data for further
information or analysis. The example below represents a method to cite the information;
however, publications often have their own style manuals, and we suggest you
check reference formatting instructions.
Maps (Dynamically Generated)
Identify the name of the mapping service as well as the name of the person
generating the map.
GENERAL FORMAT:
Author [if there is one]. "Map title" [format]. Scale. Computer database
title [format]. Edition. Place of production: Producer, Date of copyright or
production. Using: Author. Computer software title [format]. Edition.
Place of production: Producer, Date of copyright or production.
EXAMPLE:
"Massachusetts Breast Cancer Incidence 1995-2002" [map]. Scale 1" =
40 miles. Silent Spring Institute MassHEIS [computer files]. Anytown, MA: Jane
Doe, 2006. Using Silent Spring Institute MassHEIS [online application]. Newton,
MA: Silent Spring Institute. 2006.
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What
data will you include in the future?
Silent Spring Institute is currently working on adding
data on drinking water and surface water quality. We are
also adding census data that describe demographic charateristics
(e.g. age of home, education, and income), births to smokers,
low birth weight, autism, and blood lead levels in children.
Please use the Feedback box on the HEIS entry page to suggest
other data sets you would like to be included in the future.
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___________________________________________________________________________________________ How do I use
ArcGIS with MassHEIS?
You can use ArcGIS to view and analyze MassHEIS data
by using an ArcIMS Service. This will allow you
to load the MassHEIS map services as 'layers' within ArcGIS,
exposing them to the wide array of tools that are available
with ESRI's ArcGIS suite. To load the services in ArcGIS,
go to File - Add Layer - Add ArcIMS Server, and use the
address: http://library.silentspring.org.
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What is the
ArcIMS Server address?
http://library.silentspring.org
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How can I save data
to my own machine?
ArcMap will not allow you to save data to your own machine
when the data is being drawn from ArcIMS Services. However,
as a work around you can do the following;
- select all or part of the layer you wish to save to
your machine
- right-click and select'save as layer file'
- when the layer file appears in the menu, you can save as normal (i.e. data-export)
In future, we hope to offer data download capabilities
via a metadata browser, but this is not offered for the
pilot.
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Can
I look at metadata without having to use the online application?
We are currently developing a metadata browser, however
you may browse the metadata
index to learn more about the data we are hosting.
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What coordinate
system is MassHEIS data presented in?
State Plane MA Mainland, NAD83 meters. This is the same
as MassGIS.
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