PRELIM LEC 1 (1): INTRODUCTION TO BIOSTATISTICS

Question 1

INTRODUCTION TO BIOSTATISTICS

are the basic sciences of public health

Answer 1

Epidemiology and biostatistics

Question 2

INTRODUCTION TO BIOSTATISTICS

is a branch of applied mathematics which deals with the collection, organization, presentation, analysis and interpretation of data.

Answer 2

Statistics

Question 3

INTRODUCTION TO BIOSTATISTICS

is the application of statistics to problems in the biological sciences, health, and medicine

Answer 3

Biostatistics

Question 4

INTRODUCTION TO BIOSTATISTICS

is the study of the distribution and determinants of health, disease, or injury in human populations and the application of this study to the control of health problems

Answer 4

Epidemiology

Question 5

ROLE OF QUANTITATIVE METHODS IN PUBLIC HEALTH

Generate a hypothesis
 Based on scientific rationale
 Based on observations or anecdotal evidence
(not scientifically tested)
 Based on results of prior studies
 Examples of a hypothesis
 The risk of developing lung cancer remains constant
 in the last five years
 The use of a cell phone is associated with developing
 brain tumor
Vioxx increases the risk of heart disease

Answer 5

Address a public health question

Question 6

ROLE OF QUANTITATIVE METHODS IN PUBLIC HEALTH

 Survey study is used to estimate the extent of the disease in the population
 Surveillance study is designed to monitor or detect specific diseases
 Observational studies investigate association between an exposure and a disease outcome  They rely on “natural” allocation of individuals to exposed or non-exposed groups
 Experimental studies also investigate the association between an exposure, often therapeutic treatment, and disease outcome  Individuals are “intentionally” placed into the treatment groups by the investigators

Answer 6

Conduct a study

Question 7

is used to estimate the extent of the disease in the population

Answer 7

Survey study

Question 8

is designed to monitor or detect specific diseases

Answer 8

Surveillance study

Question 9

investigate association between an exposure and a disease outcome  They rely on “natural” allocation of individuals to exposed or non-exposed groups

Answer 9

Observational studies

Question 10

also investigate the association between an exposure, often therapeutic treatment, and disease outcome
 Individuals are “intentionally” placed into the treatment groups by the investigators

Answer 10

Experimental studies

Question 11

ROLE OF QUANTITATIVE METHODS IN PUBLIC HEALTH

 Numerical facts, measurements, or observations obtained from an investigation to answer a question
 Influences of temporal and seasonal trends on the reliability and accuracy of data
 Examples:  The number of lung cancer cases from 1960–2000 in the United States
 The number of deaths from cardiovascular diseases in Whites and African Americans from 2000–2004

Answer 11

Collect data

Question 12

ROLE OF QUANTITATIVE METHODS IN PUBLIC HEALTH

Descriptive statistical methods provide an exploratory assessment of the data from a study
 Exploratory data analysis techniques
 Organization and summarization of data
 Tables  Graphs  Summary measures

Answer 12

Describe the observation/data

Question 13

methods provide an exploratory assessment of the data from a study

Answer 13

Descriptive statistical

Question 14

ROLE OF QUANTITATIVE METHODS IN PUBLIC HEALTH

 Inferential statistical methods provide a confirmatory data analysis  Generalize conclusions from data from part of a group (sample) to the whole group (population)
 Assess the strength of the evidence  Make comparisons  Make predictions  Ask more questions; suggest future research

Answer 14

Assess the strength of evidence for/against a hypothesis; evaluate the data

Question 15

methods provide a confirmatory data analysis

Answer 15

Inferential statistical

Question 16

ROLE OF QUANTITATIVE METHODS IN PUBLIC HEALTH

 The study results will prove or disprove the hypothesis, or sometimes fall into a grey area of “unsure”
 The study results appear in a peer-review publication and/or are disseminated to the public by other means
 Consequently, the policy or action can range from developing specific regulatory programs to general personal behavioral changes

Answer 16

Recommend interventions or preventive programs

Question 17

2 TYPES OF STATISTICS

Answer 17

Descriptive statistics
Inferential statistics

Question 18

deals with the collection and presentation of data and collection of summarizing values to describe its group characteristics

Answer 18

Descriptive statistics

Question 19

deals with predictions and inferences based on the analysis and interpretation of the results of the information gathered by the statistician

Answer 19

Inferential statistics

Question 20

numerical characteristics or attribute associated with the population being studied

Answer 20

Variables

Question 21

2 TYPES OF VARIABLES

Answer 21

Categorical or Qualitative Variables
Numerical - Valued or Quantitative Variables

Question 22

example: Gender, Eye color, Blood Type, Civil Status, Socio Economic Status

Answer 22

Categorical or Qualitative Variables

Question 23

 Discrete - is a variable whose values are obtained by counting
 Continuous - is a variable whose values are obtained by measuring such as temperature, distance, area, age, height

Answer 23

Numerical - Valued or Quantitative Variables

Question 24

is a variable whose values are obtained by counting

Answer 24

Discrete

Question 25

is a variable whose values are obtained by measuring such as temperature, distance, area, age, height

Answer 25

Continuous

Question 26

4 SCALES OF MEASUREMENT

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NOMINAL SCALE ORDINAL SCALE INTERVAL SCALE RATIO SCALE

Question 27

Sex, Nationality

Answer 27

NOMINAL SCALE

Question 28

 ordered but differences between values are not important  e.g., Likert scales, rank on a scale of 1..5 your degree of satisfaction  e.g., pain ratings

Answer 28

ORDINAL SCALE

Question 29

 ordered, constant scale, but no natural zero  e.g., temperature (C,F)

Answer 29

INTERVAL SCALE

Question 30

 ordered, constant scale, natural zero  e.g., height, weight, age, length

Answer 30

RATIO SCALE

Question 31

is defined as groups of people, animals, places, things or ideas to which any conclusions based on characteristics of a sample will be applied

Answer 31

Population

Question 32

subgroup of the population

Answer 32

Sample

Question 33

SLOVIN'S FORMULA:

Answer 33

n= N _______ 1+N(e)2

Question 34

SLOVIN'S FORMULA where: n – _______ N – population 1 – constant e – sampling error

Answer 34

Sample

Question 35

SLOVIN'S FORMULA where: n – sample N – _______ 1 – constant e – sampling error

Answer 35

Population

Question 36

SLOVIN'S FORMULA where: n – sample N – population 1 – _______ e – sampling error

Answer 36

Constant

Question 37

SLOVIN'S FORMULA where: n – sample N – population 1 – constant e – ________

Answer 37

sampling error

Question 38

STAGES IN THE SELECTION OF A SAMPLE

Answer 38

1. Define the target population 2. Select a sampling frame 3. Determine id a probability or nonprobability sampling method will be chosed 4. Plan procedure for selecting sampling units 5. Determine sample size 6. Select actual sampling units 7. Conduct fieldwork

Question 39

2 TYPES OF SAMPLING TECHNIQUES

Answer 39

PROBABILITY SAMPLING NON-PROBABILITY SAMPLING

Question 40

the sample is a proportion (a certain percent) of the population and such sample is selected from the population by means of some systematic way in which every element of the population has a chance of being included in the sample o Numerical - Valued or Quantitative Variables  Discrete - is a variable whose values are obtained by counting  Continuous - is a variable whose values are obtained by measuring such as temperature, distance, area, age, height SCALES OF MEASUREMENT A. Nominal Scale  Sex, Nationality B. Ordinal Scale  ordered but differences between values are not important  e.g., Likert scales, rank on a scale of 1..5 your degree of satisfaction  e.g., pain ratings C. Interval Scale  ordered, constant scale, but no natural zero  e.g., temperature (C,F) D. Ratio Scale  ordered, constant scale, natural zero  e.g., height, weight, age, length SAMPLING TECHNIQUE  Population o is defined as groups of people, animals, places, things or ideas to which any conclusions based on characteristics of a sample will be applied  Sample o subgroup of the population  SLOVIN’S FORMULA: n= _____N_____ 1 + N(e)2 where: n – sample N – population 1 – constant e – sampling error STAGES IN THE SELECTION OF A SAMPLE 1. Define the target population 2. Select a sampling frame 3. Determine id a probability or nonprobability sampling method will be chosed 4. Plan procedure for selecting sampling units 5. Determine sample size 6. Select actual sampling units 7. Conduct fieldwork  Types of Sampling Techniques 1. Probability Sampling  the sample is a proportion (a certain percent) of the population and such sample is selected from the population by  Randomization is a feature of the selection process rather that an assumption about the structure of the population  More complex, time consuming and more costly

Answer 40

Probability sampling

Question 41

The sample is not a proportion of the population and there is no system in selecting the sample. The selection depends upon the situation.  No assurance is given that each item has a chance of being included as a sample  There is an assumption that there is an even distribution of characteristics within the population, believing that any sample would be representative

Answer 41

Non-probability sampling

Question 42

4 EXAMPLES OF PROBABILITY SAMPLING

Answer 42

Simple Random Samping Stratified Random Sampling Systematic Sampling Cluster Sampling

Question 43

Lottery Method This is the most popular and simplest method

Answer 43

Simple random Sampling

Question 44

the population is split into non - overlapping groups (“strata”), then simple random sampling is done on each group to form a sample

Answer 44

Stratified random sampling

Question 45

This method is widely employed because of its ease and convenience.  A frequently used method of sampling when a complete list of the population is available It is also called Quasi - Random Sampling

Answer 45

Systematic Sampling

Question 46

When the geograpical area where the study is too big and the target population is too large

Answer 46

Cluster sampling

Question 47

2 EXAMPLES OF NON-PROBABILITY SAMPLING

Answer 47

Convenience sampling Purposive sampling

Question 48

 no system of selection but only those whom the researcher or interviewer meet by chance are include the sample.  process of picking out people in the most convenient and fastest way to immediately get their reactions to a certain hot and controversial issue  not representative of target population because sample are selected if they can be accessed easily and conveniently.    Advantage: easy to use Disadvantage: bias is present it could deliver accurate resultwhen the population is homogeneous

Answer 48

Convenience sampling

Question 49

 the respondents are chosen based on their knowledge of the information desired.

Answer 49

Purposive sampling

Question 50

specified number of persons of certain types are include in the sample.

Answer 50

quota sampling

Question 51

sample is taken based on certain judgements about the overall population

Answer 51

Judgment sampling