Measurements and Errors of measurement/Data source & Quality

Question 1

Defining who has the disease

Answer 1

PROBLEMS WITH INCIDENCE AND PREVALENCE MEASUREMENTS:

PROBLEMS WITH NUMERATORS

Question 2

.Problems due to difficulties in diagnosis

Answer 2

Some Possible Sources of Error in Interview Surveys

Question 3

• participant may chose not to respond or alter his response

- responds to please the interviewer

Answer 3

Problems associated with the study participant

Question 4

• not recording or incorrect recording
• incorrect questioning
• biased by knowing the hypothesis being tested and may probe more intensively in one group than in another

Answer 4

Problems associated with the interviewer

Question 5

• Selective undercounting of certain groups e.g. Ethnic minority
• Different studies use different definitions so comparison of results is difficult
• For a rate of make sense, every one in the group represented by the denominator must have the potential to enter the group represented by the denominator. This is not that simple.

Example: Uterine cancer rates
Hysterectomy

Answer 5

PROBLEMS WITH DENOMINATORS

Question 6

An index of the severity of a disease from both clinical and public health standpoints

Answer 6

Mortality

Question 7

Can also be used as an index of the risk of disease

Answer 7

Mortality

Question 8

Easier to obtain than incidence data for a given disease, however when a disease is mild and not fatal, it is not a good index for incidence

Answer 8

Mortality

Question 9

2 conditions where mortality rate is a good reflection of incidence rate:

Answer 9

When case-fatality is high (i.e. untreated rabies)
When duration of disease is short (survival)
i.e Pancreatic cancer – where mortality is good surrogate for incidence

Question 10

the disease or injury which initiated morbid events leading directly or indirectly to death → underlying cause

Answer 10

Cause of death

Question 11

excludes information pertaining to the immediate cause of death, contributory causes, and those causes that intervene between underlying and immediate causes

Answer 11

Underlying cause of death

Question 12

Is a true experiment in which patients are assigned randomly to a study category (treatment), and are then followed forward in time, and the outcome is assessed

Answer 12

RANDOMIZED CONTROL TRIAL (RCT)

Question 13

meaning the sample members are allocated to treatment groups by chance alone so that the choice reduces the risk of possibly biasing factors

Answer 13

RANDOMIZED CONTROL TRIAL (RCT)

Question 14

• lack of representativeness

- “a process at any stage of inference tending to produce results that depart systematically from the true values”

Answer 14

BIAS

Question 15

Occurs when two factors are associated with each other and the effect of one is confused with or distorted by the effect of the other

Answer 15

CONFOUNDING BIAS

Question 16

are factors (exposures, interventions, treatments, etc) that explain or produce confounding

Answer 16

Confounder

Question 17

• Creates problems in statistical analysis

- Affects comparability of treatment and control groups

Answer 17

Problems with Sample Attrition

Question 18

Treatment maybe so effective that patients believe themselves to have been cured and cease taking medications; successes disappear from treatment, leaving treatment appearing less effective than what it really is

Answer 18

Problems with Sample Attrition

Question 19

• Replacement of drop-outs not advisable

- Drop-out rates should be considered in sample size estimation

Answer 19

Problems with Sample Attrition

Question 20

indicator of therapeutic usefulness and effectiveness and should be considered when drawing conclusions from trials

Answer 20

Drop-out data can be used

Question 21

the extent to which a measurement or study reaches the correct conclusion.

Answer 21

VALIDITY

Question 22

The degree to which a test is capable of measuring what it is intended to measure

Answer 22

VALIDITY

Question 23

The degree to which the result of an observation are correct for the particular group studied

Answer 23

INTERNAL VALIDITY

Question 24

determined by how well the design, data collection, and analyses are carried out and are threatened by all the biases, and random variation

Answer 24

INTERNAL VALIDITY

Question 25

Extent to which the study’s results can be applied to those beyond the study sample

Answer 25

EXTERNAL VALIDITY (Generalizability)

Question 26

Assuming that the results of the study are true, do they apply to my patients as well?

Answer 26

EXTERNAL VALIDITY (Generalizability)

Question 27

expresses the validity of assuming that patients in a study are comparable with other patients

Answer 27

Generalizability

Question 28

Due to differences or changes in the standardized diagnostic criteria (i. e. diagnostic custom) used by most physicians - example: Hypertension, Rheumatoid arthritis

Answer 28

THE OBSERVER

Question 29

Due to differences or changes in the application of diagnostic criteria by individual clinician example: rounding off quantitative measurements (BP), carelessness, or simple ignorance

Answer 29

THE OBSERVER

Question 30

International Classification of Diseases, 8th revision – reported a 15% increase deaths due to IHD ICD 9th revision reported reduced number of death

Answer 30

THE SYSTEM used for codifying and classifying observations of the phenomena of interest

Question 31

Errors due to behavioural responses Example: - Recall bias - Response bias - Response-set bias (strongly agree; strongly disagree

Answer 31

THE SUBJECT being examined, interviewed or observed

Question 32

the interviewer tends to elicit a desired or expected response by wording a question in certain way

Answer 32

Experimenter bias

Question 33

the subject’s experience or knowledge that he is being observed or studied changes his behaviour or performance, and possibly certain physiologic functions – Placebo effect

Answer 33

Hawthorne effect

Question 34

Temporary elevation of BP due to anxiety

Answer 34

THE SUBJECT

Question 35

Errors due to mechanical failures or problems with equipment

Answer 35

THE INSTRUMENT used for making measurements or combining information

Question 36

Errors due to conceptual problems involving the availability or adequacy of specific tests

Answer 36

THE INSTRUMENT used for making measurements or combining information

Question 37

Errors due to analytic or scaling problems of combining from two or more items or tests to form an overall index or indicator of the factor (disease) of interest Example: combining different scores from survey stems, clinical symptoms or lab tests to derive an index of depression

Answer 37

THE INSTRUMENT used for making measurements or combining information

Question 38

- Human errors of data processing - encoding, key punching, data abstraction and transcription, improper use of computer software, and bugs and viruses in the software

Answer 38

THE DATA PROCESSING EFFORT

Question 39

the extent to which a measure produces the same result at different times for the same subjects

Answer 39

INTRA-OBSERVER RELIABILITY

Question 40

- the extent to which a measure produces the same observation on each subject regardless of who makes the ob

Answer 40

INTER-OBSERVER RELIABILITY

Question 41

- the extent to which all items or test making up a composite measure (index) reflect the same underlying construct

Answer 41

INTERNAL CONSISTENCY

Question 42

those obtained by the investigator to answer specific questions he has in mind

Answer 42

PRIMARY DATA

Question 43

- interviews, PE, laboratory tests | - more expensive and more difficult to obtain but more accurate and up-to-date

Answer 43

PRIMARY DATA

Question 44

- those that are actually gathered by other individuals/investigators

Answer 44

SECONDARY DATA

Question 45

- already published reports or existing records from agencies or institutions

Answer 45

SECONDARY DATA

Question 46

- more readily available but maybe incomplete

Answer 46

SECONDARY DATA

Question 47

may be difficult to access because of confidentiality of data

Answer 47

SECONDARY DATA

Question 48

Define the population at risk | Census statistics

Answer 48

DENOMINATOR DATA

Question 49

- Define the events or conditions of concern | - Statistics from health, disease, birth, and death registries and surveys

Answer 49

NUMERATOR DATA

Question 50

- Natality, mortality, marriages, divorces, adoptions | - Total births/deaths, deaths by specific cause, infant mortality, etc

Answer 50

DATA ON VITAL EVENTS

Question 51

- Existence of disease based on abnormal PE and/or laboratory findings - Prevalence or incidence of specific diseases

Answer 51

DISEASE STATISTICS

Question 52

Hemoglobin, blood sugar levels, blood pressure

Answer 52

Data on physiologic &/or pathologic conditions

Question 53

Activities and performance of health agencies

Answer 53

Data on health resources and service

Question 54

. Number of households with sanitary water source; amount of pollution in the air; noise level

Answer 54

Statistics pertaining to the environment

Question 55

Total number of people in an area according to age, gender, urban

Answer 55

Demographic data

Question 56

. KAP of people regarding health practice

Answer 56

Socio-cultural data

Question 57

required to be registered within ____ days by birth attendant or the family or any person who knows the occurrence of the event, at the Local Civil Registry

Answer 57

Birth: 30 days

Question 58

Uses of Birth Certificate

Answer 58

1 To prove the fact of birth -For proving parentage; for inheritance of properties;for settlement of insurance; for legal dependency; to establish identity; for tracing ancestry; for planning child health programs 2 To prove date of birth - For entrance to school, automobile license; right to vote; for marriage; for entering civil service, social security benefits; settlement of pensions; enlistment to armed forces; issuance of professional licence; proof of legal age 3 To prove place of birth -For issuance of passport, immigration and to establish citizenship Patters of fertility Population estimate – based on the knowledge of births, deaths, and migration Population projection Public Heath Programs

Question 59

Who can file the birth certificate?

Answer 59

Parents Legal guardian Midwife/ Physician In case of a lost baby (foundling), the rescuer or founder

Question 60

Required by law to be registered by medical attendant, family, local health officer, or anybody who knows such event

Answer 60

Death

Question 61

Some aspects of person’s death are not reflected

Answer 61

circumstances of death

Question 62

It should be filed within _____ after the time of death

Answer 62

48 hours

Question 63

Uses of Death Cartificates

Answer 63

1 To prove the fact of death - For lifetime insurance claims and for settlement of estates 2 To prove facts about the deceased for circumstances of death - For access to or termination of government services such as health cards, pensions, etc - For medical, health research and for statistical purposes - To provide an ongoing mortality data resource for measuring health problems, guiding health programs, and evaluating health promotions and disease control activities

Question 64

Cause of Death

Answer 64

The disease or injury that started the physiological processes that led to the termination of life

Question 65

Disease or injury that led to the death | Ex: Pneumonia

Answer 65

Immediate Cause of Death

Question 66

Pertains to the sequelae or complications that gave rise to the immediate cause Ex: Stroke

Answer 66

Antecedent Cause of Death

Question 67

> Root disease; other significant conditions contributing to death but not actually related to the immediate cause; most important of the three Ex: Diabetes Mellitus Example: A patient has diabetes mellitus. He then had a cerebrovascular accident and was hospitalized because of this. While in the hospital, he developed pneumonia and died.

Answer 67

Underlying Cause of Death

Question 68

- Special records kept for special diseases, usually chronic, like cancers - Should contain all cases of the illness that occur in the catchment area - Contains pertinent information on the course of the illness, medications, etc - One look at the register will tell how many prevalent cases are there, how many have died or recovered

Answer 68

Disease Registers

Question 69

List of Notifiable Diseases by the DOH Required by law to report to DOH Attending physician Maybe undernotified because of > Ignorance of the law > Non-caring attitude to report the case > Not all sick people seek medical help

Answer 69

Disease Notifications

Question 70

Taken at regular interval of years provide complete enumeration of population’s profile

Answer 70

Census

Question 71

Sources of data in instances where the investigator need specific variables in specific scales of measurement

Answer 71

Surveys

Question 72

Is the data available not long after the date of occurrence of the event covered? Data is not often submitted on time because: a. Health worker has too much work b. Too many forms to be filled up c. Transportation and communication problems

Answer 72

TIMELINESS

Question 73

both completeness of coverage and completeness in accomplishing all the items in every form Q: Does the data cover the entire geographic area and target population?

Answer 73

COMPLETENESS

Question 74

refers to how close the measurement of the data is to its true value

Answer 74

ACCURACY

Question 75

refers to the repeatability or consistency of the information

Answer 75

PRECISION