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HI comprehensive


undefined, object
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What are the steps in the standard development process
early implementation
What is ANSI
American National Standards Institute
What is CEN?
The European committe for standardization
What is HISB?
Health Informatics stds board descended from the Healthcare informatics standards planning panel formed by ANSI in 1992 in response to a request from CEN to identify a single national organization to represent US standardization efforts
What is HIPAA?
The Health Insurance Portability and Accountability Act
What is ASTM?
American Society for Testing and Materials
Committee E31 charged with medical information standards
example of scripting language
Compare imaging parameters for Digital XRay, MRI, CT, US, and NM
XR CT US MRI Pixels 2,048 512 512 256
X2,560 512 512 256
# of images 2 60 30 100
Bytes/study 20m 30m 7.5m 12m
Compare digital image to analog image
analog image is reality
digital image is a model of reality
How fast do you have to take pix to capture something in motion?
real time: 30 frames a sec will get a clear image of a beating heart
compare pixel vs voxel
pixel is a picture element
voxel is a volume element
What is CCD
charge coupled device is a device used to convert existing film-based images to digital format
What is PACS
picture archiving and communication system
How do you store images
as bit map 10 mb/exam
CD holds 650mb
DVD holds 4.6gb
magneto-optical holds 2.6-5.2gb
Compare Lossless and Lossy compression algorithms
Lossless 2-3/1 compression
Lossy 20/1 compression
Describe difference between JPEG and MPEG
JPEG is video
MPEG has sound
What is the greatest resolution that the human eye can appreciate
cannot resolve greater than 1000 x 1000 on a 20 inch monitor
how do you retrieve images
index images--tag with text

retrieve by content--query is an image
very difficult
four types of image manipulation
global processing-gray scale windowing

segmentation (difficult)-extract region of interest

feature detection-volume of heart

classification- type of object found, identify abnormality
what is indexing
process of assigning tags from an ontology to a set of content
ex. MeSH used by Medline
Describe difference in manual and automatic database building by web search engines
auto spider program
adv updated frequently
adv can have large database
disadv difficult to search
disadv no quality control

manual ontology like Yahoo
adv qual control
adv can be characterized for retrieval
disadv slow & expensive
How do web search engines order the results
how closely result matches query-Excite

Measure of link popularity--Google
(most do this now--very effective)

By date--Pub Med
Explain transistor water faucet analogy
gate turned off--charges don't flow
faucet turned off--water doesn't flow
what is combinational logic
no memory
use and and exclusive or gate together to carry over
what is Moores Law
Computer speed and memory double every 18 months
Example of declarative and procedural languages
declarative--prolog and lisp

procedural-pascal and perl
Describe difference between abstraction and representation
Abstraction--examination of data and selection of an item from terminology with which to label it

Representation--as mjuch detail as possible is coded
Describe difference between pre and post coordinated vocabulary
Pre--Enumerate all possibilities before hand
can be computationally intractable

Post--Give units and rules for combining units to be more expressive
What is ICD-9
International classification of Diseases
codes used to define diagnosis for billing (originally used for reporting mortality data)
What is DRG
Diagnosis related groups
developed at Yale for use in prospective Medicare payment
What is CPT
current procedural terminology
used to document procedures for billing
What is LOINC
Logical(originally laboratory later ext)observations, identifiers, names and codes
What is DSM
Diagnostic and statistical manual used by the American Psychiatric Association to define psychiatric disorders
What is GALEN
European consortium AIM developin a reference model for medical concepts using structured meta knowledge (SMK)
When drawing a decision tree, what shape is a decision node?
What are Read codes
diagnosis codes created by James Read for use by the British National Health Service
What is Gabrieli Medical Nomenclature?
Developed by Elmer Gabrieli at the University of Buffalo
Single large hierarchy with extreme pre-coordination
What is MESH?
Medical Subject Headings used by NLM & Medline to facilitate retrieval
When drawing a decision tree, what shape is a chance node?
What is NDC
national drug codes (FDA)
used in US
no hierarchy
codes may be reused
not as comprehensive as WHO drug dictionary which is an international classification of drugs
what is UMLS
Unified (Uniform)medical language system created by Don Lindberg and Betsy Humphreys at NLM

Consists of:
Meta-thesaurus--semantic info about biomedical concepts and the relationships between them

Semantic network: network of general categoreis or semantic types to which all the concepts in the Meta-thesaurus have been assigned

Specialist Lexicon--contains syntactic info about biomedical terms
When drawing a decision tree, what shape is a outcome node?
triangle on it's side
Explain the three risk attitudes.
risk averse--risk itself has neg. value
risk neutral--risk itself 0 value
risk seeking--risk itself has pos. value
How do you represent 1,608,258 in
Binary, Octal, and Hexadecimal?
Binary 110001000101001000010
Octal 6105102
Hex 188A42
What is objective probability assessment?
Initial estimate should be based on the prevalence of the disease in the population.
What is the difference between privacy and confidentiality?
privacy is the desire to control disclosure of personal information

confidentiality is limiting the release of information

security is the general term
What is prevalence?
The probability of an event in a population.
Define data integrity
Data has not been improperly modified
which could happen:
intentionally--by hackers or viruses
unintentionally--by transmission errors or incorrectly entered data
How to you assess pt preferences?
Standard gamble--at what probability does the subject reach indifference between the health state and the standard gamble

Time trade-off--How much time with the disease would you be willing to give up to be in ideal health. (still looking for the point of indifference)

Visual-analog scale--draw on a line scale between perfect health and death
What are the rules of normative decision making?
Probability rule--everything can be assigned a probability

Order rule--prospects can be ordered according to preference

Equivalence rule--Given prospects A>B>C we can assign a probability p such that the certainty of B is equivalent to a gamble between A and C

Substitution rule--An equivalent deal can be imbedded in a more complex deal

Choice rule--If A>B>C then you would pick A over B and B over C
Define accountability
Users must be acccountable for their use of the data--use audit trails

authentication identifies the user to system

authorization give user right to access certain parts of the system or perform certain actions
Define cryptography
Use of mathematical tools to protect data.Based on probability and information theory. Does not replace other security efforts.
define cipher
algorithm that takes plain text and outputs ciphertext (encoded equivalent)
Explain difference between public and private keys
public key-assymetric
each party has public key know to everyone and a private key known only to them. Something encoded with one key can only be decoded with the other

If I use my private key to encode something it verifies my identity. If I want to send you a private message, I encode it with your public key and only you will have the private key to decode it.

private key-symmetric
sender and receiver share a secret key which is used to encode and decode ? how do you transmit the key securely if you aren't in same geographic location?
relatively efficient and no need for PKI (public key infrastructure)
What is a certificate?
Requires a trusted third party to verify identity and issue certificate.
What is Bayes Theorem?
[(Sens)(prev) + (1-Spec)(1-prev)]
What are the uses of a clinical information system?
Data acquisition
record keeping and access
communication and integration of info
information storage and retrieval
data analysis
decision support
Give an example of competing criteria in a clinical information system?
availability vs. security
structure vs. expressivity
What is HL7?
Both a health information standard and a health information standards development organization
Name four ways of creating a standard
Ad hoc ex DICOM
De Facto ex Microsoft Windows
Government mandate ex HCFA HB92 ins form
Consensus ex HL7
Explain the differences between representativeness, availability, and anchoring and adjustment.
They are all heuristics to estimate probability

Representativeness is how similar this case is to others--prev experience may be biased or atypical and the presentation may be atypical.

Availability is how easily we recall similar events--events we remember more easily are judged to be more probable.
However dramatic, atypical, emotion-laden or more recent events are more memorable.

anchoring and adjustment is making a initial estimate and adjusting it based on experience--usual mistake is to adjust too little with new info
What is sensitivity?
Probability of Positive test given that you DO have the disease
What is specificity?
Probability of Negative test given that you do NOT have the disease.
What's the perfect test?
100 % sensitivity
100 % specificity
does not exist
What is a gold standard?
The best that you can do in a given situation
What assumptions must you make to use Bayes theorem?
Conditions are mutually exclusive and collectively exhaustive
Sequence of tests are conditionally independent
What do you want in a screening test--high sensitivity or high specificity?
High sens gives you many false positives but will miss very few cases
High specificity will give you less false positives but will miss more cases.
What is expected value decision making?
How we SHOULD make decisions. The goal is to choose the alternative with the maximum utility
Normative decision making
What is decision analysis?
Its a logical process that leads to a good decision (not necessarily a good outcome)
What is the definition of medical reasoning?
Reasoning under uncertainty
Explain probability
The likelihood(p)of eventoccurring
must be between 0 and 1
Ex. coin toss
p[heads] is .5
p[tails] is .5
Must sum to 1
p[heads] + p[tails]= 1

Events a & b are independent if occurrence of one doesn't influence the occurrence of the other.

Probability of two independent events occurring together is denoted by
p[a,b]or p[a&b]

The probability of two independent events both occurring is given by the product of the individual probabilities
What are heuristics?
rules of thumb not guaranteed to work
What are data interchange standards
application independent standards that permit sender to transmit to receiver all data required to accomplish a specific transaction set, which is usually defined for a particular trigger event.

Does not say what receiver will do with the data. It's driven by economic benefits of sharing data.
What is DICOM
Digital Imaging and COmmunications in Medicine--a standard developed ad hoc by the American College of Radiology (ACR)and the National Electrical Manufactureres Association (NEMA)

It was needed to communicate digital images to allow PACS (picture archiving and communication systems) and help new equipment integrate with existing systems
Define and Describe the OSI
It stands for Open Systems Interconnection. It was developed as a communication model.
Layers are:
1 physical
2 data link
3 network
4 transport
5 session
6 presentation
7 application
define and describe TCP/IP
It stands for transmission control protocol/internet protocol
1 Network Interface
(roughly equiv to layers 1&2 OSI)
2 Internet
(equiv to layer 3 OSI)
3 Transport
(equiv to layer 4 OSI)
4 Application
(equiv to layers 5,6,& 7 OSI)
What is different about version 3 of HL7
Version 2.3.1 was widely implemented.
Version 3 is in draft form but includes two information models
RIM--reference information model
Meta Model--methodology & modeling
What is an ontology, give an ex
An explicit specification of concepts in a domain and the relationships between them
HL7 RIM is an ontology
Give the current version of the HL7 standard and explain how it works
Trigger--event that creates need for data flow

Initiating system constructs an hl7 message from application data and sends it to receiver system

Responder receives message and
validates the message syntactically against semantic rules
if it fails--reject message generated
if it succeeds--passes the message to application layer of the receiving system which creates a response and sends it back to the initiator.

Initiator passes message to initiating application.
Message--sent as a delimited ASCII string comprised of:
segments--defined as logical grouping of:
data fields--defined as string of characters with many different types of data
What is RIM
HL7 Reference Information Model which is a class model that includes:

--subject classes which are the classes whose information must be actively managed by the clinical health information system
--attributes for each of the classes
--relationships between the classes
--state transition diagram to express the lifecycle for each of classes
what is an interaction model
it defines the behavior of systems that communicate using HL7 messages
what is a message design model
the message format defined from the RIM to meet the message requirements of each interaction
What are the five reasons to evaluate?
1 promotional
2 scholarly--reusable knowledge
3 pragmatic--make it better
4 ethical (is what we're doing safe?)
5 Medico-legal (liability)
Give an example of computational intractability
Traveling salesman story
what is the shortest tour length to visit all the places on his route
What is NP
non-deterministic polynomial
a class of problems that can be solved in polynomial time
Have to you evaluate algorithms?
By how they scale with increasing input sizes
What is O notation
O(1)--constant, doesn't differ with n
O(n)--scales linearly
O(n-squared)--nested loop quadratic
O(constant-raised to the n)--exponential steep curve
what is the difference between an objectivist and a subjectivist evaluation
objectivist (logical-positivist)
properties can be measured and agreed on by rational observers

Subjectivist (intuitionist-pluralist)
what is observed depends on the observer and there can be legitimate discussion regarding the same observation
Merit depends on context
Exercise in argument, always equivocal in some light
List four objectivist evaluations and describe
--comparison-based-one thing compared to another under controlled conditions

--objectives-based-does the resource meet the designers objectives (use benchmarks)ex usability studies

--decision facilitation seeks to help people make decisions so data collection methods are designed to answer questions being posed, tend to be used in early stages to help guide resource development

--goal free-evaluators are blinded to the designer's goals and attempt to understand all of the effects of the resource, not just specific questions
List four subjectivist evaluations and describe
quasi-legal- mock trial with formal adversary proceeding to judge resource

art criticism- critic uses the resource and then writes a review. ex software reviews

professional review- panel of experienced peers who spend several days in the environment where the resource is installed and draft a report either at the sight or soon after. ex site visits

Responsive/illuminating- the goal is to understand rather than judge so all viewpoints are to be represented. It is an ethnographic method (investigators immerse themselves in the environment)
What are the stages of technology assessment
Technical characteristics ex response time

Efficacy (effect of the resource on the process of care)

Outcomes much more difficult to do
comprehensive clinical, economic, and social outcomes (ex. QALY)
Compare internal and external validity
internal validity--conclusions drawn from the specific circumstances of the experiment are justified

external validity--conclusions can be generalized
List types of bias and describe
Assessment--feelings bias measurement
overcome with blinding

Allocation--assign easier cases to one overcome with randomization

Hawthorne effect--performance improves if people know they are being studied

Checklist effect--if given a form, better data collection and better decisions

Placebo effect--some people get better because they think they are supposed to
What is QALY
quality adjusted life year
how much is a year of life worth
arbitrary cut-off is $50,000
Who incurs cost and who reaps benefits?
What is an algorithm
a procedure or formula guaranteed to solve a problem
explain the conflict between structure and expressivity
the more structured(numbers, characters and discrete observations) the data is, the easier it is to put it in an electronic format. The more expressive (free text)is is the more computationally intractable it becomes
what can humans do better than computers
recognize patterns
list inadequacies of paper record
inaccessible-can only be in one place, difficult to transport, illegible, difficult to "back-up", difficult to search.

static-can't change presentation based on need, can't abstract (how did the infection spread)

can't process data--for assessing correlations automatically, quality control, compliance with clinical guidelines, unable to do validity tests
why doesn't everyone use CPR
Mostly non-technical reasons
cost vs benefit --what's in it for me?
What's the down side to CPR
paper charts usually lost or destroyed one at a time so although computers fail less often when they do it is more catastrophic

security breeches are ususally individual with a paper chart but an electronic breech could access thousands of charts and could be done from outside the facility
What is Problem-oriented medical record
1969 Larry Weed organized data around the problems a patient had
What is managed care and how does that relate to the CPR
managed care is an attempt to shift the financial risk from the insurance companies to the physician who makes the decisions regarding tests, etc

THe CPR can provide the information that is critical to efficient care
How do you judge a particular CPR
how comprehensive is the information
Duration of use and retention of data
degree of structure in the data
how accessible is the system
What is one of the fundamental issues for CPR implementation
-how to get old data into system
hard-clinical data
-how to enter new data into system
coded vs free text?
What is case management
attempt to avoid the artificial seperation of different specialities by providing a coordinator who fills the role that was traditionally filled by a primary care physician
what is patient monitoring
repeated or continuous observations or measurements of the patient or his physiological function for the purpose of guiding decisions
ex vitals--TPR
ex EKG
what are the levels of patient care
sub-acute--skilled nursing& extended
outpatient with home care
explain Nyquist frequency
how much data is really required, the Nyquist frequency says data should be collected at twice the expected frequency of change (if EKG can change 150/sec you have to sample at 300/sec

--more data-more accurate representation
--more data-more storage space & computing power that's needed
What are the two major types of human error?
planning-original action was incorrect

execution--slips, the correct action does not proceed as intended
--automatic action (like driving home when you intended to stop at store)

--incomplete action that is similar to familiar intention (putting a zip disk in a floppy drive)

--associative action which is similar but not correct (picking up desk phone when cell phone rings)

--loss of activation of current intention (forgetting an idea when interrupted)
what are the requirements for good decisions
accurate data-not just more
pertinent knowledge

problem-solving skills---how to combine data and pertinent knowledge
Explain the Leeds abdominal pain system
an early decision support system in Leeds, England that
used Bayes theorem to decide among seven possible diagnoses which required him to assume those seven diagnoses were mutually exclusive and collectively exhaustive (and they are NOT)

System was better than physicians but Could not duplicate results elsewhere
what is the fatal flaw of rule-based support systems
they don't scale well with growing knowledge base
What is the HELP system
It was a HIS + an event-driven decision support system developed at the Latter Day Saints (LDS) hospital in Salt Lake City.

Fore-runner to the Arden syntax which is a standard specification for definition and sharing
what is arden syntax
"shareable guideline representation formalism"
what is evidence-based medicine and what are the common targets
making medical decisions based on the evidence

Evidence can be strong or weak
It can be conflicting
It can be non-existant

Targets are
common diseases
bad diseases( cost/morbidity&mortality)
diseases you can do something about
What are clinical practice guidelines
systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances
What is Defensive medicine
Considering EBM std versus what can be defended in court
What two systems were sucessors to the 1989 Ardex syntax
HELP LDS Hospital in Salt Lake

CARE Regenstrief Institute in Indianapolis
Describe the MLM
medical logic module is the stream of text stored in an ASCII file in statements called slots

slots have a name and a body

Slots are grouped into three categories

Slot contents are
text list sperated by ;
coded-specific value
structure-specific syntax
What kind of quidelines is the Arden syntax well suited for vs less suited for
well suited-labs

less suited-complex branching guidelines where decisions effect the flow through the decision tree
What is a knowledge based system
"smart" system with large relational structure that operates on a general level of understanding not statistics
what is clinical practice
application of general knowledge to a specific situation
What is just-in-time knowledge
retrieving the necessary knowledge when you need it (at the point of care)
Describe CHIN
community health information network would have allowed analysis of aggregate data
Never "took off"
Stds problem
Political challenges
Competition challenges
What is HEDIS
Health Plan Employer Data and Information Set developed by the NCQA (National Committee for Quality Assurance)to assess performance of HCO with an emphasis on preventative care
What is Healthy People 2010
It is a government program challenging individuals, communities, and professionals to take specific steps to ensure that good health and long life are enjoyed by all
What are the three universally reportable health events
death of a fetus
what is consumer informatics
field of study concerned with the broad issues related to biomedical information as it applies to health care customers.
what is public health informatics
Field of study concerned with biomedical information as it relates to the population as a whole. Concerned with disease prevention and more efficient care
what is the ideal program for consumers
medically sound
easy to use
interactive-value beyond printed book
fast & reliable
Readily available
Who said, "Any doctor who could be replaced by a computer deserves to be."
Warner Slack
What groups of patients are looking for health information on the internet
The well (60%)are looking for preventive medicine and information the same way they look for other products

The Newly Diagnosed (5%) is searching frenetically and covering a lot of ground in the first few weeks after their diagnosis

The Chronically ill and their caregivers (35%)

All patients are also looking for alternative and complementary medicine
Who is driving the eHealth trend
younger female
What are health consumers looking for on line
What are the two biggest concerns of consumers seeking health information on line
What are the most valuable features sought by the health consumer
email to doctor
retrieving lab results
checking insurance eligibility
tracking reimbursements
What are the information areas most searched by consumers
Specific conditions
Diet & Nutrition
Womens health
What is the digital divide
The same populations that have higher incidence of disease (minority ethnic groups, poor, elderly) are also less likely to use the internet
Compare the current health care system to the 21st century goals
episodic care vs continuous care
MD idiosyncracy vs patient idiosyncracy
Professional control vs patient control
info management vs knowledge mgt
Experience driven decisions vs Evidence based decisions
Safety as individual vs safety as system
secrecy vs transparency
reactive vs proactive
cost reduction as goal vs waste reduction as goal
individual care givers vs cooperation amongst the healthcare team
What are the tools for eDisease mgt
secure email
online health records
tailored knowledge bases
physician, pt-centered, population-centered decision support tools
remote information capture and monitoring capability
portable computing devices
wireless connections
good batteries
typing skills
what are critical issues for eDisease mgt
Privacy, confidentiality, and security
Data ownership
Established therapeutic relationships
Medical ethics
Reimbursement reform
Training of both patients & providers
What is a disruptive technology
One that allows the individual to do something which previously he couldn't do because it required the skill of a professional
What is an example of a disruptive technology
OTC drugs
Describe the four types of patients
Accepting (8%)-do whatever the doctor says

Informed (55%)-still rely on doctor but typically go on line to inform themselves about their condition

Involved (28%)-these patients view themselves as partners with their physician in making decisions

In control (9%)-these patients feel best suited to determine their own care.
How do we evaluate health information on line
Manner of presentation
Give an example of quality criteria
JAMA Journal of the American Medical Association) benchmarks

HON(Health on the Net)Code
evaluation only episodic

DISCERN (European web site with validated questionaire)
What is the self-correction hypothesis
If there is adequate participation in any forum and incorrect information is posted then someone else will reliably and quickly post correcting information.
what are decision analysis steps
1 Decision Tree
2 Calculate EV of each alternative
3 Choose alternative with highest EV
4 Use Sensitivity Analysis to test the conclusions
Define Expected value
(Utility(or QALY) X probability) of each chance alternative summed
what is true negative rate (TNR)
# of nondiseased people with - test/
# of nondiseased people
Define likelihood ratio
Liklihood ratio is the prob of a certain result in diseased people/ prob of same result in nondiseased people


Describe the different types of bias in measurement
spectrum bias-when study population includes only those with advanced disease and those who are healthy volunteers. Advanced disease may be easier to detect-artificially high TPR

test referral bias-occurs when a positive index test is a criterion for ordered the gold-standard test-artificially high TPR and artificially low TNR

Test-interpretation bias develops when the interpretation of the index test affects that of the gold standard test or vice versa--artifical concordance between the tests
what is referral bias
most studies are done by specialists (whose patient base is mostly referral of the worst cases)and therefore atypical when compared to the general population
Compare Consulting DSS versus Critiquing DSS
Consulting is oracle,you give it the data and it gives you the plan

Critique--sounding board, you propose a plan and it evaluates it expressing agreement or suggesting reasoned alternatives
Discuss three types of imaging resolution
spatial--related to sharpness, measure of how well it distinguishes point that are close together. Determined by number of pixels/image area

contrast--measure of the ability to distinguish small differences in intensity. In digital images this is determined by the number of bits/pixel

temporal--measure of time needed to create an image. considered real time application if it can generate pictures at a rate of at least 30/sec
systemized nomenclature of medicine-Originally created for the American College of Pathologists. The third version is greatly expanded and internationally used
CT clinical terminology
RT reference terminology
What is a PN junction
ordinary diode made of conductive crystal material (silicon)with impurities added
usually arsenic for n-type semiconductor
usually aluminum for p-type semiconduct
can affect flow of electrons by reversing polarity
What is ICPC
International classification of primary care used by some countries
What is MYCIN
an early decision support system developed by Shortliffe that was a rule-based system to help choose the appropriate treatment for bacterial infections of the blood

It is an example of backward chaining--take the hypothesis and then see if it is true

Whereas forward chaining--evaluates the data and looks for a hypothesis that may be true
What is NP hard
A problem is NP-hard if an algorithm for solving it can be reduced to one of a known set of NP problems.

NP-hard if solving it in polynomial time would make it possible to solve all problems in NP in polynomial time.
What is RLE
run length encoding
more efficient compression for large pattern images
What is the Arden Syntax rationale
Arose from need to make medical knowledge available for decision making at the point of care

Need to standardize the way medical knowledge is integrated in a HIS to make medical knowledge and logic explicit and allow sharing between institutions
what are the five functional components of a CPR system
-integrated view of patient data
-clinical decision support
-clinician order entry
-access to knowledge resources
-integrated communication support
what are the indications for CPR
information is critical to pt care
-prevent duplicate tests
-communicate between providers
-decision support for better decisions
CPR's are tools to improve use of info
what is Internist-1
Early DSS, QMR quick medical reference is the descendant that is now marketed commercially.

attempt to bottle the "brain dump" of Jack Meyers (internal medicine specialist)
what is NP complete
a problem that is a subset of NP that is also NP-hard. A solution for an NP complete problem would solve all problems in NP
what is bottleneck
one part of the computer system is slowing down the entire process even though other parts could function faster
what is difference between observations and knowledge
observations are just data about the world

knowledge is the interpretations and implications of the data
what is disease management
organizes different disciplines around the care of a specific disease ex diabetes

Rules and protocols for common (particularly high cost) diseases
what is sensitivity analysis
test of validity of an analysis over wide range of assumptions about probabilities and values or utilities.
Describe sequential logic in the processor
output from first gate is used as input to second and output form second gate is used as input to first
causes set-reset (AKA flip-flop)
uses feedback to store a bit
what is the difference between recall and precision as related to Pub Med
Recall is the percentage of relevant documents that are retrieved .

Precision is the percentage of documents retrieved that are relevant.

recall = # relevant art. retrieved/
# relevant art. in database
precision = # relevent art.retrieved/
# art. retrieved
what is true positive rate (TPR)
# of diseased people with a + test/
# of diseased people

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