Biostat Module 9 Lecture PDF

Module #9 LECTURE in the 20th century. The latter’s contribution has INTRODUCTION TO BIOSTATISTICS had great impact on the contemporary statistical The Meaning of Statistics...

Module #9 LECTURE in the 20th century. The latter’s contribution has INTRODUCTION TO BIOSTATISTICS had great impact on the contemporary statistical The Meaning of Statistics procedures. The term statistics refers to a set of pertinent Biostatistics activities such as collection, organization, is the branch of applied statistics that concerns the presentation, analysis, and interpretation of application of statistical methods to medicine and quantitative data. biological problems. It is a field of study which deals with the It is the analysis of data derived from biological mathematical characterization of a group or group sciences and medicine. of items. Experiments in biosciences are generally carried Collection of data refers to the process of out to give quantitative or numeric answers to gathering numerical information. investigate questions. Methods of gathering pertinent information include The fields of contribution of Statistics an interview, questionnaire, and experiments, Statistics observations, and documentary analysis. is used in almost all fields of human endeavor. Once the data are gathered, the next step in In public health, a doctor may be interested with statistical inquiry is the presentation of data in the number of residents in an area who contract a appropriate tablets or graphs. new strain of flu virus in a certain number of Such tables refer to frequency distributions which months. may either be one-dimensional or In education, a researcher might want to know if two-dimensional. new methods of teaching are better than the The graphical presentation includes bar graphs, traditional ones. frequency polygon, pie-graph, and many others. In sports, a statistician may keep records of the Analysis of data refers to the activity of number of hits a basketball player gets in a season describing the properties or behavior off data of of games. the possible correlation of different quantities or In business, a car dealer may look at past records variables. for a specific month to decide what type of Finally, interpretation has to be made based on automobiles and how many of each type to order the preliminary activities and other statistical for that month of next year. methods. Such methods involve testing the Agriculture significance of the results. the varies of the plant we should grow and the Background and the Development of Statistics best combinations fertilizers, pesticides and The present state of the science and art of densities statistics is an outcome of very active researches Biology of the statisticians during the past 400 years or so. research and experimentation in life processes An Englishman John Graunt in 1662 observed that plants and animals promote growth or prolong life percentages of deaths from suicides, accidents, Business and various diseases remained remarkable production, distribution, sale merchandise, auditing constant throughout the years. and accounting procedures Notable contributors in the development of statistics Demography were: composition, distribution, growth of human Abraham de Moivre who discovered the equation populations, birth, death, immigration rates, social of the normal distribution in 1773 and economic standing of the population Carl Gauss who made its derivation from study of Economics errors in repeated measurements which he called production, resources, trade, labor force, it Gaussian distribution. consumers and procedure responses to products Sir Francis Galton (1811-1911) and Karl and changes in prices, advertising system and (1857-1936) developed the theory of regression distributions and correlation. Education Adolf Quetelet, a Belgian is referred to as the teaching-learning process, measurement and Father of Modern Statistics. He considered evaluation, educational studies enrollment, statistics as the queen of the sciences, until some management and finance authors have defined it more technically to serve Engineering other branches of knowledge, the common design and test performance, quality control characteristic has been the multiple definitions that Environmental studies have been written about the subject. He the increase of birth defects and death toll near established a commission of statistics which nuclear power plants became a model for many organizations of Government statisticians. taxes and wages, materials resources movement William S. Gosset developed the small- sample of population election theory and further developed by Sir Ronald Fisher Health Such objects have common attributes which are public health program hospitalization problems of grouped with the objective of determining certain medical care occurrence and cost disease, trends that might be useful to the researcher. accidents and handicaps Sampling Medicine refers to the method of getting a small part of the causes, diagnosis, treatment, and prevention of population. communicable and non-communicable diseases That small part that serves as the representative of Research and statistics the population is called a sample. probability’s statistical theories and methods A sample is a subgroup of the population. Social sciences Samples are taken from the population so as it social system and social welfare, behavior represents the population characteristics or traits. patterns of groups of people The measures of the population are called Sports parameters, while those of the sample called points made out of so many attempts from the field estimates or statistics. of foul from the line such as basketball football One of the important distinctions that researchers Thus statistics can be used for many purposes. As the make is the contrast between the population and a activities and functions of the various fields of endeavor sample become more and more complicated the greater A simple problem that is usually encountered by becomes the use of statistics. In general, uses of the researcher determining the sample size is on statistics may be described by the following statements: the percentage of the sample size to the a. statistics gives a precise data population size. b. statistics can predict the outcome of an experiment or the If we take part of a given population as a sample, behavior of an individual then not all members of the population shall be c. statistics can be used to set hypothesis taken into consideration. Areas of Statistics In this regard, we have to consider the margin of Statistics has already grown into a field that is varied and error that will be obtained during due to sampling. extensive. To compute for the value of the sample size is Statistical evaluations may be classified into relative to the population size N, we have the two-sub-areas. formula 1. Descriptive Statistics refers to the field of statistics that includes the methods of collecting, classifying, graphing, and averaging data with the objective of simply describing the properties or characteristics of the data at hand. Thus, the task of the statistician on this area is simply to select a few procedures, do some averaging, and eventually be able to identify significant figures of the given data. Where: N is the population size; e is the margin of error; n is Examples: the sample size Based on the research conducted by DOH, 63% of Two types of variables or data those found to have diabetes were not that they 1. Qualitative variables have such disease represent differences in quantity, character, or kind Cigarettes were associated with 29% of the 4,470 but not in amount. civilian deaths in 1989 Examples are sex, birthplace or geographic locations, 2. Inferential statistics religious preference, marital status, and eye color. it demands somewhat higher degree of critical 2. Quantitative variables judgment and advanced mathematical models. are numeric in nature and can be ordered or This field is concerned with drawing conclusions or ranked. generalizations from organized data. Examples of quantitative variables are weight, Thus the task of the statistician here is not just to device height, age, test scores, speed and body ways to give summary description of the data but to devise temperatures. ways, to test significance of the results. Quantitative variables are further classified as Examples: either discrete or continuous Drinking red wine may reduce the risk of heart Discrete variable disease by 12% a variable whose values can be counted using Aspirin may lower the rate of heart attack by 50% integral values such as the number of enrollees, Carrot juice may strengthen the lungs drop outs, graduates in a certain college, deaths, Sample and Population number of employees. Discrete variable assumes Population refers to the totality of all objects under integral values study. Continuous variable 3. Interval Scales a variable that can assume any numerical value indicate an actual amount and there is equal unit over an interval or intervals. of measurement separating each score, Examples include height, weight, temperature, time, specifically equal intervals. pressure in a tire, and a number of miles driven. Continuous Interval data do not only include “greater than” and variables yields decimal or fraction. “less than” relationships, but also has a limit of A variable can be dependent or independent measurement that permits us describe how much depending on its use. more or less one object possesses than other. To predict the value of the other independent Examples: variable is the predictor while the dependent The difference between 2 and 3 is the same variable is the variable whose value is being difference between 3 and 4. predicted. The 4 kilos of corn is twice that of 2 kilos For example, to predict the value of sunlight on the Fahrenheit temperature growth of a certain plant, the dependent variable is Score on test as a measure of knowledge the growth of the plant while the independent Aptitude test scores variable is the amount of sunlight exposed to the 4. Ratio data plant. are similar to interval data, but has an absolute SCALES OF MEASUREMENT OF DATA zero and multiplies are meaningful. Assigning a numerical value to a variable is a Ratio data include all the usual measurements of process called measurement. length, height, weight, area, volume, density, A scale of level of measurement relates to the velocity, money, and duration. rules used to assign scores and is an indicator of These are the highest level of measurement. the kind of information that the scores provide. Examples: The scale to which measurement belong will be Election vote important in determining appropriate methods for Speed of a production line data description and analysis. Average daily delivery of 1000 packages per day Four levels of scales of measurement: Horsepower of motorcycle engines 1. Nominal Data Salaries of cashiers of day –night grocery stores use numbers for the purpose of identifying name or membership in a group or category. All quantitative variables are measured on a nominal scale. Observations can be classified and counted without a particular order or ranking imposed on the data. Examples: Classifying survey subjects as male or female (gender) Classifying residents according to zip codes Political party (KBL,LABAN,LP) Religion (Catholic, Protestant) Marital status (married, divorced, widowed, separated) 2. Ordinal Data connote ranking or inequalities. One category is higher than the other one. In this type of data, numbers represent “greater than” or “less than” measurements, such as preference rankings. Convalescing patients may be characterized as unimproved, improved, and much improved. Individuals may be classified according to socioeconomic status as low, medium, or high Examples: Social class or incomes o Ordering of viands by preference Responses to items on an instrument (always, sometimes, never) Grades (A,B,C,D,F) Rating scales ( based on scores or percentages)