2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
EVENT INFORMATION
DESCRIPTION – Disease Detectives allows students to use their investigative skills in the study of
disease, injury, health, and disability in populations or groups of people with a focus on the FOODBORNE
ILLNESS for 2017.
There is a three topic rotation for Disease Detectives: Environmental Quality, Population Growth,
and Food Borne Illness – each on a two year rotation
2017-Some Causes of Food Borne Illness
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Bacteria
Viruses
Parasites
Protozoa
Natural toxins
Other pathogenic agents (as Prions)
Some Environmental Causes of Public Health Problems:
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Air pollution , Smoking, Inducers of Asthma
Flooding health problems, Drought problems
Extreme heat, UV exposure
Lead contamination, Pesticides, Chemical Spills
Water pollutants, Heavy metals
Ventilation pollutants
Noise induced hearing loss
Waste and toxic substance
Food contamination
Some Population Growth Causes of Health Problems
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Water Quality, Water Pollution, Water Demands
Sanitation Needs
Growth of Slums and Household Environment
Environmental Degradation
Air Pollution
Infectious Disease Outbreaks
Rapid Spread of Disease via Public Transportation and Air Travel
Food Quality and Food Contamination
Lack of food in poor nations vs. unhealthy fast food and drinks in technological societies
Availability of health care for the poor and the aged
People moving into uninhabited areas = new pathogens
as Lyme Disease and Ebola
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
RULES – Rules are available from your Tournament Director.
• 2017 should appear at the bottom by the page number.
• BE SURE TO CHECK THE RULES for Event Parameters and suggested topics.
• At www.soinc.org see the Event Information and Event Supervisor sections
• Rules clarifications are available at www.soinc.org under event information.
FORMAT – Disease Detectives may be exam based, station based, or a combination of both
It is most often an inquiry-based written exam with 2-3 outbreak scenarios.
Division C may do some statistical analysis-< 10% of competition.
EVENT NEEDS
ROOM TYPE – Classroom when run as an inquiry based exam or a room with tables if run as
stations.
HELPERS – 2 or 3 helpers are needed to proctor and grade in addition to the event supervisor. If
possible it is beneficial to have volunteers who are assigned to grading and others assigned to
ranking. This is especially true if the event is run in 2 or more sessions. This ensures that the
grading process is continuous and rushed.
EQUIPMENT – Any materials needed for the competition.
• One exam per team
• Grading keys for helpers
• One answer sheet per team
• Basic office supplies (pens, pencils, stapler, staple removers, etc.)
TIME NEEDED FOR SETUP
• If possible go by the event room prior (~1 hour) to the exam to properly arrange the room.
• When run as an inquiry-based exam, all teams can compete at once if a large enough
room is available.
• You just need time to check in and distribute the exam and answer sheets.
• This event usually takes a long time to grade so it is a good idea to run it early in the day.
• Using an answer sheet helps to organize answers for students and makes grading quicker.
PREPARATION FOR COMPETITION
TIME-LINE FOR PLANNING - You will need to know the number of teams competing.
• Teams consist of two students so plan accordingly. Be sure you have enough time to prepare
the questions, answer keys, and answer sheets.
• Writing a good exam takes time. If possible begin the writing process as soon as possible.
• Possible sources of outbreak scenarios are
o Morbidity and Mortality Weekly Report
o Emerging Infectious Diseases
o Journal of Infectious Diseases
o Journal of the American Medical Association
o New England Journal of Medicine
ORGANIZING CONTENT – Be sure to cover the topics presented in the rules and give
appropriate emphasis to each area.
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
WRITING QUESTIONS
• Format and material of the Division B and C event is similar except that the level of
reasoning and math skills should be consistent with the grade level.
• Differences between the two levels should be reflected in both the type of questions asked
and the scoring rubrics. Testing the process is most important – students are taught to relate
the 10 step
procedure to the scientific method.
• Competitions may be written using actual data from an outbreak or it may be a hypothetical
outbreak with hypothetical data.
• Fill in or multiple choice questions are easier to grade.
• Free response questions should have a rubric to assist in scoring.
• The Science Olympiad website www.soinc.org has event information with training materials
for students, and internet links which may assist you in writing questions.
The CDC has information on their website www.cdc.gov/excite as well as previous exams.
• The philosophy of Science Olympiad is that the competition be inquiry- based to emphasize
process skills and mental challenges using suggested content.
• Balance the content so that it reflects the content described in the rules. Students are
expecting to see all of the topics listed in the rules to be reflected in the competition.
• Develop questions which are easy to grade.
• Multiple choice, matching, fill-in-the blank questions are preferable. They are quicker to
grade and allows volunteers completely unfamiliar with the event to assist in grading.
For example:
Okay: List three things that are true of case control studies.
• Although the question is limited to 3 responses there are more than three possible
correct answers. The grader will have to be familiar with case control studies to
properly grade all possible responses. This will likely take from a few seconds to
several minutes.
Better: Which of the following statements are true about this case control studies? Circle
the letters of all that apply.
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Finding adequate numbers of controls can be difficult
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Not vulnerable to bias
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Exposure is determined by memory or records
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Requires little time to conduct
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Can study multiple outcomes
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Used when the population is not well-defined
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All of the above
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The above question has a definite answer (a, c, d, f) and can be graded by anyone. There are
also multiple ways to provide partial points which can help avoid the use of tiebreakers.
Objective Questions require a letter or few words and can be graded quickly
Free Response or Essay Questions require several words or a paragraph and take longer to
grade. They are good questions to use as tie breakers.
Answers to short answer questions should require no more than one to two sentences and be
very specific. Including questions with multiple interpretations and are open to various
answers can be very difficult to grade.
For example:
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
Disease detectives use three pieces of information to characterize an outbreak. What are they?
Answer: person, place and time
There are only three correct answers to this question. No others are acceptable. A grader with
no knowledge of epidemiology could grade this question.
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For questions requiring calculations points should be given for both showing their work and
the correct answer.
Graphs and tables are good potential source of questions.
Develop appropriate questions so that all ties can be broken.
Be sure that all teams experience the same testing conditions.
VARING DIFFICULTY FOR SUCCESS OF MANY - To allow most students to be
successful, it may be a good idea to vary the difficulty of questions!
ANSWER SHEET ORGANIZATION – Set up the answer sheet so it is easy for students
to use and easy for your team to grade. Include team name, team number, student names,
as well as a place to record raw score, rank, and points. Be sure you have enough answer
sheets for each team. It may be a good idea to put team names and numbers on the
answer sheets ahead of time.
ANSWER KEY AND SCORING RUBRICS
• Questions will be assigned point values.
• Students will be ranked from highest to lowest score.
• Ties will be broken by pre-determined tie-breaker questions.
• Have extra answer sheets so your helpers can assist you in grade the competition.
• Be sure each section is graded by the same person.
RUNNING THE EVENT
SET UP TIPS (Exam format)
• Be sure you have a copy of the exam for each team.
• It may be advisable to have a separate answer sheet for each team.
• The answer sheet will provide ease of recording answers and speed up grading.
CHECK IN TIPS– if possible, allow all teams to compete even if one or both members are
late. They may need to miss some things but they can do part of the competition.
• Check each team member for wrist bands or approved ID before giving teams
their answer sheet.
• Have extra pencils and direct students print their names on sheet.
• Direct student to turn off all non-permitted electronic devices. You may wish to have
them put in a designated spot, given to someone outside the room or placed in the student
back packs at some to be stored at a designated spot in the room.
• Allow each team to have only what is permitted in the Event Parameters.
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
TEST FORMAT:
• Hand out test packet just before the event is to begin.
• Give any directions needed.
• Two or three helpers can do the proctoring.
• If the event is run in sessions, begin grading after the first session.
• Helpers can help with grading as long as there is consistency in grading.
DEALING WITH PROBLEM SITUATIONS – have the cell phone numbers of officials
• DISQUALIFICATIONS OF A TEAM SHOULD BE RESTRICTED TO SAFETY
ISSUES, CHEATING, OR ABUSIVE AND UNSPORTSMAN-LIKE BEHAVIOR.
• Be sure that tournament officials and coaches are notified of any disciplinary action.
CHECK OUT TIPS
• Be sure to get an answer sheet and exam from each team before
you allow them to leave the competition.
• Be sure the team number, team names and member names are present and legible.
• Remind students to take all their backpacks and other possessions as cell phones.
SCORING THE EVENT – DO NOT GIVE OUT RESULTS ANY TEAM OR COACH.
CONSISTANCY IN GRADING – have the same person grade the same section for all teams.
CHECKING MATH AND RANKING – Be sure to check the math and ranking for all teams so
they are accurate. Scoring worksheets or computer programs may be available to help
with ranking.
BREAKING TIES – Break all ties and indicate on the student answer sheets and score sheet
how the tie was broken. The DECIMAL METHOD is a good way to indicate the winner
of ties. Example: If two teams have the raw score tie of 83 for, the winner of the tie
gets 83.1 while the other teams gets 83.0. If several ties are broken, you have .1 to .9
to use. This also points out scores where ties were broken.
SCORE SHEET – Fill in all information on the score sheet. Indicate how the raw scores are
ranked – high score, low score or some other method. Be sure to include raw score, rank
and points for each team. Explain how ties are broken.
SCORE COUNSELING
• Have your score sheet completed and signed before going to score counseling
• Arrange student score sheets in rank order for quick checking.
• Turn in answer sheets, a copy of the test and an answer sheet to the Score Counselor
I hope these suggestions are helpful in organizing your tournament. Comments or new ideas are always
welcome. Please send them to me at the following address.
Karen L. Lancour
312 W. Bosley
Alpena, Michigan 49707
[email protected]
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
Examples of types of performance indicators that could be used in Division B and C events at various
levels of competition.
Competition
Level
Regional/State
Division
Division B (Middle School)
List and recognize examples of different
modes of transmission
Division C (High School)
Recognize differences between study designs and
types of error.
Calculate health-related rates (attack,
incidence, prevalence, case fatality)
Calculate measures of risk (e.g. relative risk or
odds ratio) when given a description of the study
design
Calculate a simple relative risk and
describe what it means
Calculate measures based on data that is not given
but that can be readily extracted.
Interpret epi curves, temporal patterns
and other simple graphic presentations of
health data..
Recognize how gaps in information influence the
ability to extend conclusions to the general
population.
List, discuss and recognize examples of
disease causing agents (physical and
biological)
Do Statistical Analysis on Data for both
Descriptive and Analytical Epidemiology
Demonstrate an understanding and ability
to use terms such as endemic, epidemic
and pandemic; population versus sample,
association versus cause.
National
Describe various types of prevention and
control strategies (e.g. immunization,
behavior change, etc) and situations
where they might be used
Understand how units affect the relative
magnitude of a set of rates with different
units.
Recognize unmentioned factors that may influence
results and types of error.
Calculate appropriate measures of risk
when given the study design
Convert between rates with different basic units
(e.g. incidence per 10000 persons/year to incidence
per 100 persons/week).
Complete tables when given all data
needed to complete calculations.
Propose a means to evaluate the effectiveness of an
intervention or control program.
Propose a reasonable intervention to a
public health problem.
Do Statistical Analysis on Data for both
Descriptive and Analytical Epidemiology
Recognize gaps in information
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
Potential Types of Error in Data Collection (Div C)
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False Relationships
o Random Error - the divergence due to chance alone, of an observation on sample from the
true population value, leading to lack of precision in measurement of association
o Bias or systematic error in an epidemiologic study that results in an incorrect estimation of
the association between exposure and health-related event
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Non-Causal Relationships – “guilt by association”
o Confounding – occurs when the effects of two risk factors are mixed in the occurrence of
the health-related event under study - when an extraneous factor is related to both disease
and exposure
Random Error:
• Is the result of fluctuations around a true value due to sampling variability
• It can occur with data collection, coding, transfer, or analysis of data
• Affects measurement in a inconsistent manner
• Ways to reduce random error may include – increasing the sample size and reduce the variability in
measurements
Systematic Error:
• Occurs when there is a difference between the true value (the population) and the observed value
(the sample)
• The error is in the system used for measurement so it occurs in each occasion hence systematic error
• Conclusions drawn on this data will be inaccurate – too great or too little
• Validity of a study depends upon the degree of systematic error – less error equals more validity
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Internal validity – the amount of error in measurements including those for exposure,
disease, and
the association between these variables.
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External validity –relates to the process of generalizing the finding of a study to the
population from which the study is taken
Types of Bias: Describe problems in how the study is organized
• Selection bias – occurs when study subjects are selected for the study as a result of a third
unmeasured variable which is association with both the exposure and the outcome. There may be
association between diseases or between characteristics and a disease related to the admission to a
hospital for those with a disease, without the disease but with symptoms, and those with only the
characteristics of the disease.
• Information bias – occurs from systematic error in the assessment of a variable. Examples are
information bias, response bias, interviewer bias, recall bias
Confounding: the co-occurrence or mixing of effects of extraneous factors
• May lead to overestimating or underestimating the true association between exposure and outcome.
• A confounding variable would be a variable (pollution) that can cause the disease under study
(cancer) and is also associated with the exposure (smoking).
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
Statistical Concepts for Disease Detectives
Division C
Some statics may be used at Division C – but it must be less than 10% of the competition.
2016 Statistics in Science Olympiad Disease Detectives Events – Division C
Descriptive and analytic statistical methods are important in the life and health sciences and it is reasonable
to expect competitors at the high school level to demonstrate a basic competency in these methods in events
such as Disease Detectives. However, statistics is not a major component of the event and should not define
the event. Many competitors will not have had statistics and event supervisors should use it like a habanero,
sparingly if at all but with purpose. One or two short, well-placed questions are adequate.
Key principles
• Competitors should be able to use statistics – not do statistics. Competitors should not be expected to
do lengthy calculations such as paired T-tests, life tables or analysis of variance using hand calculators.
In real life, these are done with computers and statistical software packages such as SAS, SPSS or
EpiInfo.
• A more realistic approach would be to explain the study design and data collection methods and have
competitors interpret printouts from one of the above programs, to use intermediate statistics such as
standard deviations and population means to calculate test statistics or tell how changes in the value of
intermediate statistics would affect final results.
• Students should be provided formulas for all calculations and tables. It is reasonable to expect them to
know which test to use, assumptions and limitations of each but not to memorize the formulas.
• Interpretation and translation of statistics into plain language is a valid competency that fits easily into a
multiple choice format. For example, “Which of the below statements best describes these results?”
• Asking students to select a test or what test they would use to test a particular hypothesis is also
appropriate. This question may be best suited for multiple choice unless graders have sufficient
expertise to know which tests are clearly inappropriate and which are marginally appropriate and
recognize the different names for identical tests.
• Questions concerning statistics should be part of a larger scenario so that competitors can see how they
fit into the larger analysis.
• Free-standing questions on statistics just for the sake of including statistics into the competition are
contrary to the intent of the event. Event supervisors should not feel compelled to include questions
about statistics in the events if they do not fit into the larger picture.
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
Statistical Concepts for Disease Detectives
Division C
Descriptive Epidemiology - deals with the frequency and the distribution of risk factors in
populations and enables to assess the extent of a disease - the epidemiologist collects
information to characterize and summarize the health event or problem
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Used as a first step to look at health-related outcomes
Examine numbers of cases to identify an increase
Examine patterns of cases to see who gets sick and where and when they get sick
Mean – average – sum of all the given elements divided by the number of
elements. Means are typically reported when data are normally
distributed.
where sum of x scores and n = number of units in a sample
Median - The median of a series of numbers is the number that appears in the middle of the list
when arranged from smallest to largest. Medians are typically reported when data are skewed.
For a list with an odd number of members, the way to find the middle number is to take the
number of members and add one. Then divide that value by two. In our case, there are 9
numbers in the series. 9+1 = 10 and half of 10 is 5. The fifth number in the series is the median
or 14.
If the number of members of the series was even, the average of the two middle numbers
would be the median.
Mode - The mode is the number in the series that appears the most often. If there is no single
number that appears more than any other number in the series, there is no value for the mode.
Variance - measures how far the results are from the expected
results
Standard deviation - expresses how close the results are to each
is the square root of the variance
other - it
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
Standard error of the mean - standard deviation (sample standard
deviation) divided by the square root of the sample size
Confidence intervals of means - specifies a range of values within which the
mean may lie.
Z Scores for Commonly Used Confidence Intervals
Desired Confidence
Interval
90%
95%
99%
Z Score
1.645
1.96
2.576
Analytic Epidemiology - the epidemiologist relies on comparisons between groups to determine the
role of various risk factors in causing the problem
Z-test - compares sample and population means to determine if there is a significant difference. It requires
a simple random sample from a population with a Normal distribution and where the mean is known.
The Z-test is preferable when the sample number n is greater than 30. The Z value indicates the
number of standard deviation units of the sample from the population mean.
The Z measure is calculated as: z = (x - m) / SE
where x is the mean sample to be standardized, m (mu) is the
mean and SE is the standard error of the mean.
where s is the population standard deviation and n is the sample
population
size.
The z value is then looked up in a z-table. A negative z value means it is below the population mean
(the sign is ignored in the lookup table).
T-test - An independent one-sample t-test is used to test whether the average of a sample differ
significantly from a population mean, a specified value µ0
Paired T-test -The dependent t-test for paired samples is used when the samples are paired. This
implies that each individual observation of one sample has a unique corresponding member in the
other sample
Chi-square - Any statistical test that uses the chi square distribution used to decide whether there is any
difference between the observed (experimental) value and the expected (theoretical) value - Chi
square test for independence of two attributes
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2017 EVENT SUPERVISOR GUIDE – DISEASE DETECTIVES (B/C)
McNemar test for paired data - McNemar's test is basically a paired version of Chi-square test – a
form of chi-square (Χ2) test for matched paired data which is used to compare paired proportions. It
can be used to analyze retrospective case-control studies, where each case is matched to a particular
control. Or it can be used to analyze experimental studies, where the two treatments are given to
matched subjects.
Fischers exact test - a statistical test used to determine if there are nonrandom associations between
two categorical variables
Cochran Mantel-Haenszel summary odds ratio (often called the Mantel-Haenszel test) is a
hypothesis test for association between two variables while controlling for one or more nuisance or
control variables. Mantel and Haenszel proposed stratification techniques to account for
confounding.
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