Biostatistics

Question 1

Independent Variable

Answer 1

Stimuli that researchers
manipulate to create
effect

Question 2

Descriptive Statistics

Answer 2

Refers to the differmethods
 applied
 summarize and present din a form to make them eato analyze and interpretusing methods of:
 • Tabulation
 • graphical representation
• summary measures

Question 3

Inferential Statistics

Answer 3

Methods involved in order t make generalizations and
 conclusions about a target
 population, based on result
 from a sample, includes:
 • estimation of parameters
 • testing of hypothesis

Question 4

TYPES OF DATA

Answer 4

Quantitative

Qualitative

Question 5

Nominal

Answer 5

Naming or categoric variables that are not based
on measurement scales or rank order.
• # or symbols are assigned. Lowest form of
variable: (e.g., Gender, Color, Province, occupation,skin color and blood group)
• Dichotomous (binary)- which has only two
levels (e.g., Yes or No, Normal and Abnormal, Male
and Female)

Question 6

Ordinal

Answer 6

• Arranged in rank ordered categories
• (E.g., Social class, Likert scale, Satisfactory scale,
agree to disagree, murmur range, level of edema)

Question 7

. ACCURACY/ACCURATE

Answer 7

o The closeness of a measured orvalue.

o Trueness of test measurements

Question 8

PRECISION/PRECISE

Answer 8

how close measurements of the same item are to each other

Question 9

Sensitivity

Answer 9

is the test’s ability to correctly designate a subject

with the disease as positive

Question 10

Specificity

Answer 10

Is the test’s ability to correctly designate a subject

without the disease as negative

Question 11

Positive Predictive Value

Answer 11

o (PPV) is the probability that a subject with a positive

(abnormal) test actually has the disease

Question 12

Negative Predictive Value

Answer 12

o (NPV) is the post-test probability that the subject has no disease given a negative test result

Question 13

Likelihood ratio

Answer 13

It is defined as the probability of a subject who has the disease testing positive divided by the probability of a subject who does not have the disease testing positive

Question 14

SELF-SELECTION BIAS

Answer 14

o people presenting for screening tend to be healthier leading to
false sense of better outcomes

Question 15

LEAD TIME BIAS

Answer 15

o refers to the phenomenon where early diagnosis of a disease
falsely makes it look like people are surviving longer. This
occurs most frequently in the context of screening.

Question 16

LENGTH BIAS

Answer 16

o refers to the fact that screening is more likely to pick up slower-growing, less aggressive cancers, which can exist in the body longer than fast-growing cancers before symptoms develop

Question 17

OVER-DIAGNOSIS BIAS

Answer 17

o An extreme example of length bias
o aggressive search for abnormalities might actually lead to
harm and great cost without reaping any benefits

Question 18

STRATIFIED

SAMPLING

Answer 18

• Sampling method where we divide the
 population
 into
 nonoverlapping
  subpopulations or strata, and then select
  one sample from each stratum
 • The sample consist of all the samples in the
different strata

Question 19

SYSTEMATIC
SAMPLING
DESIGN

Answer 19

• Selection of the first element is at random
and selection of the other elements is
subsequently taking every k
• Sampling interval is represented by k
• kth element of the population is chosen
(k=N/n, where N is the total population, and
n is the sample size needed

Question 20

CLUSTER

SAMPLING

Answer 20

• The population is first divided into sampling
units called clusters
A sample of clusters is selected
• Every element found in each cluster is
included in the study

Question 21

MULTISTAGE
SAMPLING
DESIGN

Answer 21

• There is hierarchical configuration of
sampling units and we select sample of
these units in stages
 • The population is 1st divided into a set of
primary or first stage sampling units
• Each primary sampling unit included in the
sample is further subdivided into
secondary or second stage sampling
units, from which a sample will again be
taken.

Question 22

MEAN,

Answer 22

Most commonmeasure
 of
central
 tendency;
 “average”

Question 23

MEDIAN,

Answer 23

• The value that falls
  in the middle
  position when the
  observations are
  ranked in order
  from the smallest
  to the largest.
  • If
 number
 of
  observations
 is
  odd, the median is
  the
 middle
  number
  • If it is even, the
  median is the
  average of the 2
  middle numbers.
  • Useful on skewed
  data
 • For ordinal or
 numeric data if
 skewed

Question 24

&

MODE

Answer 24

•  The value that
 occurs with the
 greatest
  frequency in a
 set
 of
 observations
  • Used in public
 health statistics
 (top
 10
 mortality and
 morbidity)
 • For
 bimodal
 distribution

Question 25

TYPE I (Α) ERROR
 LEVEL OF SIGNIFICANCE (α)

Answer 25

Error of rejecting the null
 hypothesis when it is really
 true
 Declaring a difference when
 none exists. Similar to false
 positive test

Question 26

TYPE II (Β) ERROR
 LEVEL OF SIGNIFICANCE (α)

Answer 26

Error of NOT rejecting the
 null hypothesis when it is
  actually false
  Failing to declare a
  difference that does exist.
  Similar to false negative test

Question 27

Rejecting or Accepting a Hypothesis
Low P
p

Answer 27

Value of sample results are
 far from the population
 parameters
 Unlikely events
 REJECT HO

Question 28

High P

p>α

Answer 28

Value of sample results are
close to population
parameters
Likely events
DO NOT REJECT H O

Question 29

. EXPANSIVE

Answer 29

used to describe populations that are young and growing
characterized by their typical ‘pyramid’ shape
has a broad base and narrow top
show a larger percentage of the population in the younger age
cohorts
typically representative of developing nations, whose
populations often have high fertility rates and lower than
average life expectancies

Question 30

CONSTRICTIVE

Answer 30

used to describe populations that are elderly and shrinking
often look like beehives and typically have an inverted shape
with the graph tapering in at the bottom
have smaller percentages of people in the younger age cohorts
and are typically characteristic of countries with higher levels of
social and economic development
Base that is narrower than middle of the pyramid, usually the
result of a recent rapid decline in fertility

Question 31

STATIONARY

Answer 31

• Narrow base and a roughly equal numbers in each age group,
tapering off at the older ages, indicating a moderate proportion
of children and a slow or zero rate of growth
• used to describe populations that are not growing
• characterized by their rectangular shape, displaying somewhat
equal percentages across age cohorts that taper off toward the
top
• characteristic of developed nations, where birth rates are low
and overall quality of life is high

Question 32

SWAROOP’S INDEX:

Answer 32

Number of deaths among those
50 years and older in a calendar
year

Question 33

CASE FATALITY RATE:

Answer 33

Measures killing power of disease
High CFR means a more fatal disease.
A higher CFR is expected from a hospital statistics than from
the community

Question 34

Case-control (often

called retrospective)

Answer 34

• Define diseased subjects (cases) and non-
diseased subjects (controls); compare
proportion of cases with exposure (risk
factor) with proportion of controls with
exposure (risk factor)

Question 35

Cohort (usually
prospective;
occasionally
retrospective)

Answer 35

• In study population, define exposed
group (with risk factor) and nonexposed
 group (without risk factor)
 • Over time, compare proportion of
 exposed group with outcome (disease)
 with proportion of nonexposed group
with outcome (disease)

Question 36

Cross-sectional

Answer 36

• In study population, concurrently
measure outcome (disease) and risk
factor
 • Compare proportion of diseased group
 with risk factor with proportion of non-
diseased group with risk factor

Question 37

Clinical trial

(experiment)

Answer 37

• In study population, assign (randomly)
subjects to receive treatment or receive
 no treatment
  • Compare rate of outcome (e.g., disease
cure)
 between
 treatment
 and
nontreatment groups

Question 38

Meta-analysis

Answer 38

• Collates data from multiple independent
studies to maximize precision and power
in testing for statistical significance