Concept of Statistics | CHAPTER-7 | Research Methodology

Concept of Statistics – In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for bringing about a certain goal, like acquiring knowledge or verifying knowledge claims. This normally involves various steps, like choosing a sample, collecting data from this sample, and interpreting the data. The study of methods concerns a detailed description and analysis of these processes. It includes evaluative aspects by comparing different methods.

In this way, their benefits and drawbacks are evaluated, as well as the research goals for which they may be used. These descriptions and evaluations are predicated on philosophical background assumptions; examples include how to conceptualize the phenomena under study and what constitutes evidence in favor of or against them. In its broadest sense, methodology encompasses the discussion of these more abstract issues.

Statistics is not a new discipline but as old as the human civilization itself. The word statistics. derived from Latin word status’ meaning ‘political state”. In the old days statistics was regarded as the ‘Science of Statecraft’ and was the byproduct of the administrative activities of the state.

Emperor, kings and local chiefs used to rely heavily on statistics in framing their important administrative, military and fiscal policies. We can express meaning of statistics in several ways-

• Statistics are collection of facts.
• Statistics is a science of figures.
• Statistics refers to quantitative information
• Statistical data are collected systematically
• Statistics are numerically expressed.

Statistics refers to either quantitative information and to a method of dealing with quantitative or qualitative information.

Concept Of Statistics:

The word statistics derived from Latin word status meaning ‘political stale”. We can express meaning of statistics in several ways:-

• Statistics are collection of facts
• Statistics is a science of figures.
• Statistics refers to quantitative information
• Statistical data are collected systematically.
• Statistics are numerically expressed.

Functions of statistics:

1. It helps to emergency preparedness

2. It helps to predicting disease

3. It helps in medical studies

4. It is Used in political campaigning

5. It helps in quality testing

6. It is widely used in stock market.

7. It helps to understand the genetic afflicted with disease from parent to child

8. It helps in formulation of suitable policies.

9. It helps in data analysis/ interpretation and data generalization.

[Ref: Lecture of BNC]

Types of Statistics

1. Descriptive statistics:

It is used to describe and summarize data. Numerical measures such as average standard deviation and correlation are used to describe the features of e set of data

2. Inferential statistics:

Inferential statistics studies a statistical sample and through analysis is able to say something about the population from which the sample came. Because it is difficult to examine each member of the population individually a representative sample is used to make estimation correlations and predictions using data.

Limitations of statistics:

Statistics, although essential in many areas of activities, has its limitations also. A character which cannot be expressed in numbers, are not amenable to statistical analysis. Poor quality of data leads to fallacious conclusions. Statistics may be misused in the hands of the inexperienced. Ambitious dishonest persons may deceive the readers by presenting fictitious data.

The usefulness of statistics depends to a great extent on the ability to use ones-judgment in applying the various statistical techniques pertinent to a problem, the nature of which may be quite different in different situations.

[Ref-Prof. Md. Shahidullah/1/4]

“Statistics: Science or art”

Science is the Systematic body of knowledge. Science attempts generalization in the form of scientific principle of theory Art is the practical application of knowledge. Science teaches to know, at teaches to do. Science depends on observations, experiments and inferences, art depends on practicality and shills.

Scientific experiments and conclusions make use of principle and practices of science of statistic. Statistical phenomena are affected by multiplicity of causes. So statistics cannot measure all the phenomena accurately and exactly like physics or chemistry. Statistics depends on very much on probability. Again statistical methods are useful tools used in taking decisions and actions. For this reason statistics may be regarded as art also.

[Ref: Dr. Md. Zahid Hassan Sharif/1/2/]

Biostatistics

Now a day’s biostatistics has become an integral part of our life. It is also especially important for those who are in the various disciplines of health and biological sciences. Every day we are dealing with some forms of statistical data and information. Information comes from radio- television, newspaper and magazine, survey and surveillance, friends and colleagues and internet. Such information has got tremendous impact on our day to day lives. We are living in postindustrial and postmodern information age. We get information from collection of data.

These collected data are analyzed and interpreted for making conclusion and for taking important decisions. Statistics is not a new discipline but as old as the human civilization itself. The word statistics derived from Latin word status’ meaning ‘political state’.

Concepts of Biostatistics:

In Greek,

• Bios (means)- Life
• Metron (means)- Measured. So, it is the measurement of life.

It is a special branch of statistics which deals with different types of data pertaining to biological sciences.

Example: Measurement of crude birth rate, crude death rate, infant mortality rate, maternal mortality ratio and case fatality rate etc.

Definitions of Biostatistics:

Biostatistics is desired as, “the application of statistics to biology, medicine, nursing and other heath related professions”.

Or

It is a special branch of statistics which deals with different types of data pertaining to biological sciences e.g. measurement of crude birth rate, crude death rate, and infant mortality rate, maternal mortality ratio & case fatality rate etc.

[Ref: Dr. Md. Zahid Hossain Sharif/1/2]

Or

Biostatistics is the term used when tools of statistics are applied to the data that is derived from biological sciences such as medicine.

Or

[Ref-BK Mahajan/7/1]

Biostatistics has been defined as facts systematically collected and compiled in numerical form relating to or derived from records of vital events such as birth, death, marriage, divorce and sickness that occur in a community.

[Ref-VIRUS/1/195]

Or

It is the science and art of collection, compilation, presentation, analysis and interpretation of numerical data concerned with biological events which are affected by the multiple factors.

[Ref-JP Baride/1/1]

Classification of biostatistics/Sub-division of biostatistics:

1. Demographic Statistics- Population, Marriage and Fertility.

2. Mortality Statistics – Number and causes of disease.

3. Morbidity statistics – Illness, injury and hospitalization.

[Ref: Selim Reza/13/372]

Application of Biostatistics in Health System:

• To measure the status of a community.
• To identify the health problems with their nature, size and distribution.
• Proper planning and administration of health services Programmers.
• Estimation of future needs of community.
• For prediction of health trends.
• For evaluation of success progress or failure of heath programmers & services already in operation.
• For comparative study with other country.
• To find medical & health care needs of the community,
• For local, national and international comparisons of health status.
• For research into particular health problems.
• To fulfill suitable targets of heath trends.

[Ref: K. Park/24 +lecture]

Nationality:

• To measure the health status of the country and to identify the health problems of a community.
• To compare the health status of one part of the country with others parts.
• To compare the present heath status to that of the past and estimates future heath needs of the population.
• It provides information for planning, management, monitoring and evaluating the health services programme. Policy makers and programme managers are dependent of biostatistician information.

In physiology & biochemistry:

• To define what is normal or healthy in a population and to find range of normality in variable such as weight, height, blood pressure, serum cholesterol, ESR etc.
• To find difference between means and proportions of normal at two places.

In Clinical Medicine:

• To compare the efficacy and safety of a new drug, or new line of treatment, percentage of patients cured, relieved or died in the experiment group and control group.
• To find an association between two attributes such as overweight and blood pressure, serum cholesterol and myocardial infarction. In the documentation of medical history of disease, their courses, variability among patient etc.

In Community Medicine and Public health:

• To provide assessment of the state of health in the community and to determine the unmet heath needs of the community.
• To test efficacy and safety of sera and vaccines in the community.
• In epidemiological studies the role causative factors or risk factors are statistically tested.

In Pediatrics:

• To measure underweight, wasting, stunting children, Stating children, study of growth of children etc.

In pharmacology:

• To find the action of drug a drug is given to men to see whether the changes produced are due to the drug or by chance,
• To compare the action of two different drugs.
• To find the relative potency of a new drug with respect to a standard drug.

Medical Journal and Literatures:

• By the knowledge of biostatistics we learn to evaluate topics published in medical journals and papers read in medical conferences.

[Ref: Dr. Md. Zahid Hossain Sarif /1/3-5]

Vital Statistics

Vital statistics is the science of application of numerical data to vital events of life. It relates to information on various vital events, like births, deaths, marriages, causes of deaths etc., which are life-blood of health information system of a country.

[Ref-Prof. Md. Shahidullah/1/4]

Or

Vital statistics as defined earlier, means data which gives quantitative information on vital events occurring in life. i.e. migration, births, marriages and deaths in a given population. They form essential tools in any demographic study. Vital statistics do not include census and morbidity data but they are explained here for convenience as they are applicable to population changes just like vital events.

[Ref-BK Mahajan/7/195]

Or

The term “vital statistics” means the “data and analytical methods for describing vital events occurring in communities.” Vital events are those pertaining to human life such as births, deaths, sickness, marriages, divorces, migration etc. So vital statistics means it covers various aspects of human, nutrition and demography.

Or

[Ref-T Bhaskara Rao/2/172]

Vital statistics is that branch of statistics that deals with collection, compilation and presentation of data about the vital events of life. The vital statistics of a population are statistics such as the number of births, deaths, or marriages which take place in it.

Or

Vital statistic: It is defined as, “vital event refers to the live birth, death, total death, marriage, divorce, adoption, legitimating, recognition of parenthood, annulment of marriage, or legal separation.”

[www.wikipedia.com]

Or

Vital statistic is the brunch of statistics which Deeds unite data and vital events in human life such as Births, sickness deaths, marriages and divorces that occur in a community

[Ref: Selim Reza. 13 (372]

Sub-division of vital statistics:

1. Demographic statistics: population, marriage and Family.

2. Mortality statistics: Number and causes of death.

3. Morbidity statistics: Illness and injuries, incapacity hospitalization etc.

[Ref: Selim Reza/13/372]

Uses of Vital Statistics:

1. To describe health status of a community.

2. To diagnosis health problems of a community,

3. To determine priorities, planning and evaluation of health programmes.

4. To determine health legislation.

5. For research purposes.

6. Estimation of future needs of a community

7. For comparative study with other country.

8. For prediction of health trends

9. Estimation of future needs of a community.

10. For evaluation of success, progress of failure of health programme.

[Dr. Md. ZHS/1/209+ lecture]

Sources of Vital Statistics:

• Census.
• Vital registration method.
• Hospital and other institutional records.
• Health and demographic surveys.
• Surveillance.
• Surveys- Health Sample vial registration system notification of infectious disease
• Survey of particular disease
• Registration of vital events such as birth, death, marriage.

[Ref. Dr. Md. Zahid Hossain Sharif/1 /209]

There are three methods:-

a. Registration: Birth, Marriage, Death.

b. Enumeration: by the census and sickness survey.

c. Special measures- Notification of infectious disease, abstract of hospital case reward.

Roles of Vital Statistics of Public Health:

Vital statistics plays an important role in the field of public health such as

• It serves as a beacon to guide the public health activities.
• With continuous, adequate and purposeful compilation and proper interpretation of vital events should bring out important and salient parameters (health indicators) of health activities.
• It is, thus, the eyes and ears of health service managers, policy makers and planners alike.

Basic Tools of Measurement in Epidemiology

Basic Tools of Epidemiological Measurement:

The basic tools of measurement in epidemiology:

1. Rates

2. Ratio

3. Proportion

1. Rate: Occurrence of some particular events (e.g. disease) in a given population during a given period of time.

Numerator (X)

Rate:————-X Multiple (K)

Denominator (Y)

K= is a convenient number or bases to express the relation of X and Y

It is usual to use 100, 10,000, 100,000 or 100, 0000.

Types

i. Crude rate: Actual observation/data without change, e.g. crude birth rate.

ii. Specific rate: Actual observation/data of

a. Specific cause(e.g. TB)

b. Specific group (E.G. 5-10 years boy)

c. Specific time(e.g. July, 2000)

iii. Standardized rate: Directly or indirectly adjusted or standardized e.g. Age & sex standardize rate.

iv.

2. Ratio: A ratio shows the relative sizes of two or more values.

Numerator (X)

Ratio:—————-

Denominator (Y)

Example:

• RBC: WBC ratio
• Sex ratio
• Child-women ratio
• Doctor-population ratio

3. Proportion: The correct or appropriate relationship between the size, shape, and position of the different parts of something. It is a ratio where numerator is a part of whole things (Denominator)

Example: In a certain time in a village

The number of children with scabies

Proportion:—————-x 100

The total number of children

Different Measurement of Epidemiology:

The measurement of epidemiology:

• Measurement of mortality
• Measurement of morbidity
• Measurement of disability
• Measurement of the presence, absence or distribution of the characteristics or attributes of the disease
• Measurement of natality.
• Measurement of medical needs health care facilities, utilization of health service and other health related events
• Measurement of the presence, absence or distribution of the environmental and other factors suspected of causing the disease
• Measurement of demographic variables

Incidence & Prevalence Rate

Definition of Incidence:

Incidence, in statistics, is the rate of occurrence of something or the number of times it occurs within a population at a particular time or time period.

Or

The frequency with which something, such as a disease or trait, appears in a particular population or area.

Or

The rate at which a certain event occurs, as the number of new cases of a specific disease occurring during a certain period in a population at risk, in contrast to prevalence

Incidence Rate:

Incidence rate is the number of NEW cases of spirit disease reported during a given time interval divided by estimated population at risk. It is given by the formula-

Number of new cases of specific disease during a given time period

Incidence rate =————————————x 100

Population at risk during the perlod

It refer:

1. Only to new cases.

2. During a given period (Usually 1 year).

3. In a specified population or population at risk.

4. New spells or episodes of disease arising in a given period of time, per 1000 population.

[Ref-Neuron CM&PH 8/71]

Uses of Incidence

1. To control disease.

2. For research into-

• Etiology & pathogenesis.
• Distribution of disease.
• Efficacy of preventive & therapeutic measures.

3. For identify new cases of disease aviary, or other medical conditions.

4. Probability of developing disease over a stated period of time.

5. For reassessment and for their care planning.

( CM&PH/8/72)

Prevalence Rate:

Number of all current cases (old and new) existing at a given point in time or over a period of time in a given population.

Number of current cases old and new in a given time or time period

Prevalence rate=———————————————X1000

Estimated mid-interval population at risk

Uses of Prevalence:

1. It helps to estimate the magnitude of health/ disease problem in the community an

2. Identify potential high risk population.

3. Prevalence rates are especially useful for administrative and planning purposes, e.g hospital beds, manpower needs, rehabilitation facilities etc.

Factors Influencing Prevalence of Disease

A. Increased (1) by:

• Longer duration of the disease.
• Prolongation of life of patients without cure.
• Increase in new cases (increase in incidence).
• In-migration of cases.
• Out-migration of healthy people
• In-migration of susceptible people
• Improve diagnostic facilities (better reporting)

B. Decrees (1) by:

• Shorter duration of the disease.
• High case-fatality rate from disease, plum
• Decrease in new cases (decrease in incidence).
• In-migration of healthy people
• Out-migration of cases
• Improved cure rate of cases.

[Ref-Selim Reza/13th/61]

Different Types of Prevalence Rate:

1. Point prevalence [In a lever period of time]

• It is specified for age, sex and other relevant factors.
• The point consists of a day, reversal dues even a few weeds

2. Period prevalence (over a period of time)

3. Out-migration of healthy people.

4. In-migration of susceptible people.

5. Improved diagnostic facilities (better reporting).

Differences between Prevalence & Incidence:

[Ref Neuron CM&PH, 8/73]

Rate: A rat measures the occurrence of some particular event (development of disease or the occurrence of death) in a population during a given time period. An example of a typical rate is the death rate. It is written as below-

Number of deaths in one year

Death rate=————————-x 100

Mid-year population

Ratio: Another measure of disease frequency is a ratio, it expresses a relation in size between two random quantities. Broadly ratio is the result of dividing one quantity by another. It is expressed in the form of  x:y or x/y

An example: the ratio of white blood cells relative to red blood cells is 1: 6000 or 1/6000, meaning that for each white cell, there are 600 red cells.

Definition of GDP:

GDP Gross Domestic Product:

GDP is defined as, “An estimated value of the total worth of a country’s production and services, within its boundary, by its nationals and foreigners, calculated over the course on one year”

Definition of GNP:

GNP-Gross National Product

GNP is defined as, “An estimated value of the total worth of production and services, by citizens of a country, on its land or on foreign land, calculated over the course on one year”.

The formula of GDP:

GDP = consumption + investment + (government spending) + (exports imports).

The formula of GNP:

GNP GDP+NR (Net income inflow from assets abroad or Net Income Receipts) – NP (Net payment outflow to foreign assets).

Uses of GDP & GNP:

➤ Business,

➤ Economic Forecasting.

➤ Used to produce manufactured goods because their value is included in the price of the finished product.

➤ GNP does include depreciation and indirect business taxes like sales tax.

Difference between GDP & GNP:

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