Definition of Type 1 Errors & Type 2 Errors Effects of Type I or Type II Errors on
Mold or Environmental Testing
ENVIRONMENTAL TEST ERROR TYPES - CONTENTS: what are the two types of bad mistakes that are often made in building mold or other environmental tests & inspections. Borrowing from math and statistics we describe type 1 and type 2 errors as they apply to the building environment.
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Definition & examples of Type 1 & Type 2 errors:
Classes of testing or statistical errors applied to mold or other environmental tests, inspections & reports can be divided into two basic mistakes or error types as we explain here. We include the definitions of type 1 and type 2 errors and we give examples of type 1 and 2 errors in building inspection and testing for mold contamination.
It is important to understand these types of environmental testing mistakes in order to reduce unnecessary risks to building occupants (failing to detect and report an environmental hazard) as well as to avoid wasting people's time and money focusing on on-problems (reporting as hazards conditions that are in fact not hazardous).
Definition & Practical Examples of Type I and Type II Errors in Building Environmental Testing for Mold or Other Contaminants
Types of Reporting Errors in Buildings: definitions of Type 1 Errors & Type 2 Errors
Using building environmental testing for mold contamination as an example this article describes the types of errors that may be made by thinking, technical, or procedural errors during an investigation or test.
Type One Errors - missing a problem that's present: Occasional occurrences of certain mold genera in samples might suggest a hidden
or un-noticed mold problem in the building somewhere other than at the spot
from which the sample was collected. This is particularly true if the sample
was collected by someone who is not expert at building science, indoor air
quality, mycology, and related disciplines.
Examples of Type I errors during a mold investigation include:
Focusing on "toxic black mold" and missing a dangerous reservoir of hard-to-spot light colored mold contamination
See LIGHT COLORED MOLD
Focusing on visible mold on building surfaces, defining a remediation plan based on visible mold, and failure to consider the possibility of significant problem mold reservoirs that are hidden in building insulation or building cavities
See HIDDEN MOLD in CEILINGS / WALLS
Errors in mold sample location selection: Where to stick adhesive tape for a surface sample, or where to place an air sampling device is of critical importance. If tests are performed in building areas remote from a large problem mold reservoir the tests may find little or no indication of a problem.
See DRYWALL MOLD TESTING
Errors or variations in the mold or other environmental test conditions: building conditions such as windows or doors open or shut, presence of people or animals in the building or not, fans on or off, heat or air conditioning on or off, and variations in indoor temperature and humidity all can make 1-4 orders of variation in the level of airborne particles in a building.
Type II Errors - asserting that a problem is
present when it is not: Conversely, occasional occurrences of certain mold
in samples might also seem to point a problem in a building where in fact none
This is a greater risk where mold "counts" are used in
air sampling than it it is when surface sampling is combined with visual inspection. Occupant
indoor air or environment-related complaints or a building history of leaks
can suggest that additional investigation is in order.
Examples of Type II errors during a building mold investigation include:
To avoid both Type I and Type II errors in measuring toxic or allergenic mold exposure the
building consultant needs to understand mycology (e.g. what mold is likely to
grow in buildings), the significance of the particles found (e.g. Pen/Asp spore
chains vs. individual spores), the history, construction, and materials in the
building and the details of the inspection itself when interpreting the
importance of low levels of mold in building samples.
The articles listed below provide more examples of sources of Type 1 or Type 2 errors during building mold or environmental inspection, testing, lab sample analysis, & reporting.
Continue reading at MOLD TESTING & SAMPLING MISTAKES for more examples of how mold testing goes wrong, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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Questions & answers or comments about how to report the density or level of mold or other particles found on indoor surfaces or in indoor dust samples.
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Standards: Levels on Surfaces in Buildings provides information about allergenic, infectious, and levels of toxic
mold in residential buildings - at what point does the amount of mold in a building prove likely to be a problem for the occupants?
Mold Exposure Standards: Exposure Standards for Mold, Levels of Severity of Indoor Mold Contamination - Various Published Standards of Permissible Mold Exposure Limits: at what level is toxic or allergenic mold a problem? - What does your "spores per cubic meter of air" or "spore count" really mean - if anything?
MOLD EXPOSURE RISK LEVELS: How to Determine Mold Contamination Probability or Mold Exposure Risk Levels in Buildings Based on Visual Inspection
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
"Disease Prevention in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
US EPA: Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA: Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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