Lec Module 1-4 Flashcards
branch of applied statistics directed toward applications in the health sciences and biology.
Biostatistics
Design experiments and observational studies
Making hypotheses
Summary of data
Gathering data
Testing of hypotheses
Drawing Interferences
Application of Biostatistics
In community medicine and public health
In cancer research
In advanced biomedical technologies
In pharmacology
In ecology
In demography
In population genetics and statistical genetics
In bioinformatics
In systems biology
In agriculture
In genetics
In physiology and anatomy
2 Types of Non-Experimental Studies
- Population based studies
- Individual based studies
Population Based Studies
A. Descriptive study
B. Analytic study
This study aims to generate a hypothesis by answering the following questions,
1. What?
2. Who?
3. Where?
4. When?
Descriptive Study
characteristics (age, sex, occupation) of the individuals affected by the outcome
Person
geography (residence, work, hospital) of the affected individuals
Place
when events (diagnosis, reporting; testing) occurred
Time
Newly reported or registered disease cases compared over time, place, or person
Population estimates or other population group totals used as denominators
Incidence Study
This study aims to generate a hypothesis by answering the the “why?” and “how?” questions.
The goal of this study is to measure the association between exposure and outcome.
This type of study uses a comparison group.
Analytic Study
Example,
Ecological Study
Rates are linked to the level of exposure to some agent for the group as a whole
prepared for illustrating novel, unusual, or atypical features identified in patients in medical practice, and they potentially generate new research questions.
Case Reports
means new and not resembling something formerly known or used.
novel
Example - Case reports
Descriptive Study
Examples - Cross-sectional study, Case-control study, and Cohort study
Analytic Study
To learn about the characteristics of a population at one point in time
Does not use a comparison group
Cross-Sectional Study
To study rare diseases
To study multiple exposures that may be related to a single outcome
Case-Control Study
Can be used to find multiple outcomes from a single exposure
A cohort is a well-defined group of individuals who share a common characteristic or experience
Cohort Study/ Longitudinal Study/ Follow-up Study
study in which people are allocated at random (by chance alone) to receive one of several clinical interventions.
Randomized Controlled Trial (RCT)
The control may be a standard practice, a placebo (“sugar pill”), or no intervention at all. Someone who takes part in a randomized controlled trial (RCT) is called a participant or subject.
standard of comparison or control.
Under this branch is Clinical trial and Control trial
Randomized Study
Under this branch are Quasi-experimental study, Field trial, and Community trial
Non-randomized Study
Shares similarities with the traditional experimental design or randomized controlled trial, but it specifically lacks the element of random assignment to treatment or control.
Quasi-Experimental Research
Applies preventive interventions to healthy individuals
Field Trial
Applies intervention to aggregative units
Community Trial
Aims of Experimental Study
-To provide scientific proof of etiological factors which may permit modification or control of disease
-To provide a method of measuring the effectiveness and efficiency of health services for the prevention, control and treatment of disease and improve the health of the community.
observations of random variables made on the elements of a population or sample.
Data
researchers simply collect data based on what is seen and heard and infer based on the data collected. Researchers should not interfere with the subjects or variables in any way.
Observational Data
researchers produced this by measurement, test method, experimental design. The researcher has control over some variables.
Experimental Data
The data gathered are presented in paragraph form. Data are written and read. It is a combination of texts and figures.
Textual
Method of presenting data using the statistical table.
Tabular
The most effective manner of presenting data since it can be easily understood. Examples are Pie, Barr, Venn, Histogram, Line Diagram and Epidemic curve
Graphical
consists of table number and title
Table heading
categories which are found at the left side of the body of the table
Stubs
the top of the column
Box head
main part of the table
Body
any statement or note inserted
Footnotes
source of the statistics
Source Note
To examine a relationship between two (non-sequential) variables.
Scatterplot
where the x- axis represents some sequential variable like time, or distance along a transect (right, and below). In both cases there is an explicit (spatial or temporal) relationship between adjacent points along the x-axis, and the inclusion of the line makes the pattern of this sequence much clearer.
Line Plot
have two different y-axes, allowing variables with different scales to be plotted on the same graph. Primarily used in the same sorts of situations as line plots, where you want to compare the pattern of change in two different types of variable.
Double Y Plot
Probably the most widely used type of graph in science. This chart can be presented horizontally or vertically. straightforward to produce, and generally are either used to represent means
Bar Charts
combine features of line plots and stacked bar charts. They have similar disadvantages to the latter, though since such plots are generally used to show trends in time or space it is often easier to interpret, as the patterns of expansion or contraction of areas on the graph have a logical meaning.
Area Plot
familiar to everyone, much beloved of business graphics packages and the media, but of relatively limited use for scientific figures.
Pie Chart
plot that lets you discover, and show, the underlying frequency distribution (shape) of a set of continuous data.
Histogram
method of organizing raw data in a compact form by displaying a series of scores in ascending or descending order, together with their frequencies
Frequency table
diagram representing mathematical or logical sets pictorially as circles or closed curves within an enclosing rectangle (the universal set), common elements of the sets being represented by the areas of overlap among the circles.
Venn Diagram
A visual display of the onset of illness among cases associated with an outbreak.
Epidemic curve
is used to estimate the extent of the disease in the population.
Survey Study
is designed to monitor or detect specific diseases.
Surveillance Study
investigate association between an exposure and a disease outcome. They rely on “natural”allocation of individuals to exposed or non-exposed groups.
Observational Study
also investigate the association between an exposure, often therapeutic treatment, and disease outcome individuals are “intentionally” placed into the treatment groups by the investigators.
Experimental Study
subset of the population
sample
Summary measures computed on the sample are used to make statistical inference on the population.
Measures of Central Tendency and Measures of Variability
all items or individuals of interest.
Population
A finite subset of statistical individuals obtained from the population.
Sample
To select a portion from the population.
Sampling
Reasons for Selecting a Sample
-Complete enumerations are not possible when the population is infinite
-Results are needed in short amount of time
-Survey area is wide
-Limited resources
-Item or unit is destroyed during investigation
Stages in Sampling Collection
-Define Target Population
-Select sampling frame
-Define if probability or non probability
-Procedure for selecting sampling
-Determine sample size
-Selection of actual sample
-Fieldwork
Probability of Sampling Techniques
Simple Random
Systematic
Stratified Random
Cluster
Non-Probability Sampling Technqiue
Quota
Snowball
Self-Selection
Convenience
Purposive**
Types of Purposive Sampling
Extreme Case
Heterogenous
Homogenous
Critical Case
Typical Case
The researcher chooses a sample that is readily available in some non-random way.
Convenience Sampling
The respondent decides whether or not to participate, typically in one request without the chance for follow up.
Self Selection Sampling
It asks respondents to recommend other respondents who might subsequently be invited to take the survey.
. Snowball Sampling
The interview or study designer chooses sampled units who, by their judgment, will meet the specific purpose of the survey.
Purposive Sampling
The goal is not to be representative of views on an issue but “to look at it from all angles”.
Maximum Variance Sampling (Heterogeneous Sampling
To deeply explore the views of a group of respondents with the same characteristics.
Homogenous Sampling
It is interested in an in-depth assessment of the typical viewpoint.
Typical Case Sampling
it is interested in understanding unusual cases such as successes or failures.
Extreme Case Sampling
Studying those cases that have the most to offer in terms of understanding the population.
Critical Case Sampling
Surveying experts on a particular topic, with their expertise left to the judgment of the interviewer or study designer.
Expert Sampling
Surveying every single member of a qualifying subgroup.
Total Population Sampling
he “proportional” in the name is because the population of interest is represented almost exactly by the percentage of each cell (major demographic group) in the final survey results. “Strata may be joint or interlocking” – so you might have quotas of younger women, older women, younger men, and older men. Sometimes known as “hard quotas”.
Proportional Quota Sampling
Also known as “soft quotas”, non-proportional quota sampling captures a minimum number of respondents in a specific group.
Non-Proportional Quota Sampling
should have both coverage or a non zero chance of selecting any member of target population and external selection which is the random selection of members of population to participate in the survey.
Probability Sampling
refers to any sampling method that has the following
properties.
Simple Random Sampling
Each of the N population members is assigned a unique number. The numbers are placed in a bowl and thoroughly mixed. Then, a blind-folded researcher selects n numbers. Population members having the selected numbers are included in the sample.
Lottery method
population is divided into groups, based on some characteristic. Then, within each group, a probability sample (often a simple random sample) is selected. In stratified sampling, the groups are called strata.
Stratified Sampling
Every member of the population is assigned to only one group. Each group is called a cluster. A sample of clusters is chosen, using a probability method (often simple random sampling)
Cluster Sampling
list of every member of the population. From the list, we randomly select the first sample element from the first k elements on the population list. Thereafter, we select every kth element on the list.
Systematic Random Sampling
Combination of two probability sampling.
Multistage Sampling
Have not been summarized in any way
Ungrouped Data Also called “raw data”
Data that has been organized into a frequency distribution table.
Grouped Data
often called the average of a numerical set of data, is simply the sum of the data values divided by the number of values
mean
number that falls in the middle position once the data has been organized from lowest to highest value.
median
mode of a set of data is simply the value that appears most frequently in the set.
Mode
Only one mode
Unimodal
Two modes
Bimodal
three modes
Trimodal
four or more modes
Multimodal
easy to compute and provides statisticians and the mathematician with a better understanding of the data set how varied it is. It is the simplest approach to calculate variance in statistics.
Range
Highest value - lowest value
It looks at how spread out a group of numbers is from the mean.
It is only used to measure spread or dispersion around the mean of a data set.
It is never negative.
If all values of a data set are the same, the standard deviation is zero (because each value is equal to the mean).
Standard Deviation?
the ratio of the standard deviation to the mean.
coefficient of variation (CV)
quantity whose value changes.
variable
variable whose value is obtained by counting.
discrete variable
variable whose value is obtained by measuring.
continuous variable
measured and can take any value over an interval. The data usually falls under continuum - have infinite values.
continuous variable
Examples are - Weight of a child, volume of blood extracted, age of a patient, blood pressure of a patient, pulse rate, or temperature of a room, or time elapsed for a clotting time test.
counted and can only take certain values over an interval.
discrete variable
Examples are - Number of patients, number of medical technology books, number of doctors available.
from the Latin nomalis, which means “pertaining to names”. It’s another name for a category.
Nominal
Examples:
Gender: Male, Female, Other.
Hair Color: Brown, Black, Blonde, Red, Other.
Type of living accommodation: House, Apartment, Trailer, Other.
GenotypeLinks to an external site.: Bb, bb, BB, bB.
Religious preference: Buddhist, Mormon, Muslim, Jewish, Christian, Other.
means in order. Includes “First,” “second” and “ninety ninth.”
Ordinal
Examples:
High school class ranking: 1st, 9th, 87th…
Socioeconomic status: poor, middle class, rich
The Likert ScaleLinks to an external site.: strongly disagree, disagree, neutral, agree, strongly agree
Level of Agreement: yes, maybe, no
Time of Day: dawn, morning, noon, afternoon, evening, night
Political Orientation: left, center, right
has values of equal intervals that mean something.
Interval
Examples:
Celsius Temperature
Fahrenheit Temperature
IQ (intelligence scale)
SAT scores
Time on a clock with hands
exactly the same as the interval scale except that the zero on the scale means: does not exist. Has a true zero.
Ratio
Examples:
Age
Weight
Height
Sales Figures
Ruler measurements
Income earned in a week
Years of education
Number of children
study of a population in its static and dynamic aspects. Static aspects include characteristics such as age, gender and race while dynamic aspect involve fertility and mortality.
Demography
The study of components of variation and change in demographic variables and the relationships between them.
Demographic Analysis
The study of the relationships between demographic variables and other variables such as social and economic variables.
Population Study
structure based on gender, race or other factors that can be inserted to.
Population Composition
absolute number of a population or any demographic event occurring in a specified area in a specified time period.
Count
relation of one population subgroup to the total population or to another subgroup; that is, one subgroup divided by another.
Ratio
frequency of demographic events in population during a specified time period divided by the population “at risk” of the event occurring during that time period.
Rate
70 new cases of breast cancer per 1,000 women per year*
Incidence Rate
20 or 130 persons developed diarrhea after attending a picnic.
Attack Rate/Incidence Proportion/Risk
70 influenza case-patients in March 2019 reported in Taguig City.
Prevalence Rate
2 deaths due to HIV in Pasay City.
Case-fatality Rate
relation of a population subgroup to the entire population; that is, a population subgroup divided by the entire population.
Proportion
unchanging, arbitrary number by which rates, ratios, or proportions can be multiplied to express these measures in a more understandable fashion.
Constant
statistic that measures events occurring to a COHORT (a group of people sharing a common demographic experience) who are observed through time.
Cohort Measure
statistic that measures events occurring to all or part of a population during one period of time.
Period Measure
defined as branch of biometry which deals with data and the law of human mortality, morbidity and demography‖. These are collected, compiled and then analyse.
Vital Statistics
total process of collecting, compiling and publishing demographic, economic and social data pertaining at a specified time or times, to all persons in a country or delimited territory. It has ten years interval
Census
the method is to list all persons present in the household or other living quarters at midnight of the census day or all who passed the night there.
De facto census (in fact, whether by right or not)
all persons who usually live in the household are listed on the form whether they are present or not. Visitors who have a usual residence elsewhere are excluded from the listing but are counted at their usual residence.
De jure census (by right)
each individual is enumerated separately and characteristics of each person are recorded separately. The census covers a precisely defined territory and includes every person present or residing within its scope. defined reference period. q The census is taken at regular intervals.
Modern census
used when these changes cannot be measured directly, as for example health or nutritional status
Health Indicators
They should actually measure what they are supposed to measure
Valid
The answers should be the same if measured by different people in similar circumstances.
Reliable
They should be sensitive in the situation concerned
Sensitive
They should reflect changes only in the situation concerned
Specific
They should have the ability to obtain data needed
Feasible
They should contribute to the understanding of the phenomenon
Relevant
- Can be used for perinatal, neonatal, child, maternal and other more specific variables
- Crude death rate, cause-specific death rate, proportionate mortality, death-to-case ratio, neonatal mortality rate, post-neonatal mortality rate, infant mortality rate, maternal mortality rate
Mortality Indicators
Incidence proportion/attack rate/ risk, secondary attack rate, incidence rate/person time rate, point prevalence, and period prevalence.
Morbidity Indicators
- No of days of restricted activity, bed disability rate, work/days lost within a specific period
Event Type Indicators
Disability Rates
Limitation of mobility
- Limitation of activity
Person Type Indicator
Disability Rates
- Low birth weight, under weight (weight for age), stunting (height for age), total goiter age, iodized salt coverage, vitamin A deficiency, iron deficiency anemia (pregnant women), iron deficiency anemia (pre-school children)
Nutritional Status Indicators
- Healthcare workers per 10,000 patients
- Physicians, nurses, midwives, dentists, pharmacists (and of course medical technologists/clinical laboratory scientists)
Healthcare Delivery Indicators
- Actual coverage expressed as the proportion of people in need of a service who actually receive it in a given period, usually a year. Utilization rates give some indication of the care needed by a population, and therefore the health status of the population.
- A relationship exists between utilization of health care services and health needs and status.
Utilization Rates
- Fatigue, sleep impairment, GHQ score.
- General Health Questionnaire (GHQ-12) consists of 12 items, each assessing the severity of a mental problem over the past few weeks using a 4-point scale (from 0 to 3)
Social and Mental Health Indicators
These Indicators reflect the quality of physical and biological environment in which diseases occur and in which people live.
Environmental Indicators
- These indicators do not directly measure health. These are of importance in interpretation of indicators of health care.
- Urban population (%), % living in formal dwelling, serious crime rate per 100,000, contribution to GDP (%), unemployment rate (%), gini index (for income inequality)
Socioeconomic Indicators
Policy on: physical environment and ecology; socio-economic environment; lifestyle, behavior and risk factors; genetic endowment; and health system.
Health Policy Indicators
Income and job, housing conditions, health, education, environmental quality, personal security, civic engagement, work-life balance, infrastructure and services, mobility, and culture and leisure.
Quality of Life Indicators
