Tiêu đề 2A. Introduction to Biostatistics - Pharma Dost.pdf ✅

Biostatistics Biostatistics Pharma Dost | www.PharmaDost.info 1 BIOSTATISTICS Introduction Statistic or datum means a measured or counted fact or piece of information stated as a figure such as height of one person, birth weight of a baby, etc. Statistics though apparently plural, when used in a singular sense, is a science of figures. It is a field of study concerned with techniques or methods of collection of data, classification, summarizing, interpretation, drawing inferences, testing of hypotheses, making recommendations, etc. when only a part of data is used. Biostatistics is the term used when tools of statistics are applied to the data that is derived from biological sciences such as medicine. Any science demands precision for its development, and so does medical science. For precision, facts, observations or measurements have to be expressed in figures. Everything in medicine be it research, diagnosis or treatment, depends on counting or measurement. High or low blood pressure has no meaning, unless it is expressed in figures. Incidence of tuberculosis or death rate in typhoid is stated in figures. Enlargement of spleen is measured in fingers’ breadth. Thus medical statistics or biostatistics can be called quantitative medicine. Medical Statistics go under different names when applied in different names when applied in different fields such as:
Biostatistics Biostatistics Pharma Dost | www.PharmaDost.info 2  Health statistics in public health or community health.  Medical statistics in medicine related to the study of defect, injury, disease, efficacy of drug, serum and line of treatment, etc.  Vital statistics in demography pertaining to vital events of births, marriages and deaths. These terms are overlapping and not exclusive of each other. Application and Uses of Biostatistics as a Science In physiology and anatomy: 1. To define what is normal or healthy in a population and to find limits of normality in variables such as weight and pulse rate—the mean pulse rate is 72 per minute but up what limits it may be normal on either side of mean has to be established with certain appropriate techniques. 2. To find the difference between means and proportions of normal at two places or in different periods. 3. To find the correlation between two variables X and Y such as height and weight—whether weight increases or decreases proportionately with height and if so by how much, has to be found. In pharmacology 1. To find the action of drug - a drug is given to animals or humans to see whether the changes produced are due to the drug or by chance. 2. To compare the action of two different drugs or two successive dosages of the same drug.
Biostatistics Biostatistics Pharma Dost | www.PharmaDost.info 3 3. To find the relative potency of a new drug with respect to a standard drug. In medicine 1. To compare the efficacy of a particular drug, operation or line of treatment—for this, the percentage cured, relieved or died in the experiment and control groups, is compared and difference due to chance or otherwise is found by applying statistical techniques. 2. To find an association between two attributes such as cancer and smoking or filariasis and social class—an appropriate test is applied for this purpose. 3. To identify signs and symptoms of a disease or syndrome. Cough in typhoid is found by chance and fever is found in almost every case. The proportional incidence of one symptom or another indicates whether it is a characteristic feature of the disease or not. In community medicine and public health 1. To test usefulness of sera and vaccines in the field— percentage of attacks or deaths among the vaccinated subjects is compared with that among the unvaccinated ones to find whether the difference observed is statistically significant. 2. In epidemiological studies - the role of causative factors is statistically tested. Deficiency of iodine as an important cause of goiter in a community is confirmed only after comparing the incidence of goiter cases before and after giving iodized salt.
Biostatistics Biostatistics Pharma Dost | www.PharmaDost.info 4 Application and Uses of Biostatistics as Figures Health and vital statistics are essential tools in demography, public health, medical practice and community services. Recording of vital events in birth and death registers and diseases in hospitals is like book keeping of the community, describing the incidence or prevalence of diseases, defects or deaths in a defined population. Such events properly recorded form the eyes and ears of a public health or medical administrator, otherwise it would be like sailing in a ship without compass. Thus, biostatistics as a science of figures will tell: a. What are the leading causes of death? b. What are the important causes of sickness? c. Whether a particular disease is rising or falling in severity and prevalence? d. Which age group, sex, social class of people, profession or place is affected the most? e. The levels or standards of health reached. f. Age and sex composition of population in a community. g. Whether a particular population is rising, falling, aging or ailing? h. Which health program should be given priority and what will be the requirements for the same?
Biostatistics Biostatistics Pharma Dost | www.PharmaDost.info 5 Common Statistical Terms 1. Variable: A characteristic that takes on different values in different persons, places or things. A quantity that varies within limits such as height, weight, blood pressure, age, etc. It is denoted as X and notation for orderly series as X1 , X2 , X3 , .... Xn . The suffix n is symbol for number in the series. Σ (sigma) stands for summation or results or observation. 2. Constant: Quantities that do not vary such as π = 3.1416, e = 2.7183. They do not require statistical study. In biostatistics, mean, standard deviation, standard error, correlation co- efficient and proportion of a particular population are consid- ered as constant. 3. Observation: An event and its measurements such as blood pressure (event) and 120 mmHg (measurement). 4. Observational unit: The source that gives observations such as object, person, etc. In medical statistics the term individuals or subjects is used more often. 5. Data: A set of values recorded on one or more observational units. Data are raw materials of statistics. 6. Population: It is an entire group of people or study elements - persons, things or measurements for which we have an interest at a particular time. Populations are determined by our sphere of interest. It may be infinite or finite. If a population consists of fixed number of values, it is said to be