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Introduction and meanings of Statistics.docx
- 1. Description of Statistics Meanings of Statistics: The word Statistics seems to have been come from Latin word “Status”, an Italian word “Statista”or a German word “Statistik”. Interesting thing is that all these words from different languages have the same meaning i.e. “apolitical state” . This means information that is useful to the state/country etc. For example: information a boutthe size of the population ,armed forces, noof weapons, noof horses etc .But today this word has quite different meanings and can be divided into three main categories. 1. Numerical Facts Systematically Arranged It is collection of numerical measurements or observations related to some field of interest for some purposes. These observations may be taken from sample or population. The observations about the wages of workers are called statistics of wages. The prices of various items taken from market are called statistics of prices. Statistics of prices, Statistics of road accidents, Statistics of crimes, Statistics of birth, Statistics of deaths, Statistics of educational institutions etc. 2. Statistics as a subject: In singular sense ,we consider statistics as a subject. So ,Statistics is a science that provides methods/techniques which are used to collect, present ,analyze and interpret the numerical data and to reach any decision in the face of uncertainty.
- 2. 3. Statistics as plural of statistic: Any numerical value such as mean ,median, S .Detc. computed from sample data is called a statistic. When we have more than one such statistic’s. We use the word statistics as plural of statistic. Population: In literary sciences by population we mean to tell number of individuals/ inhabitants living in a wEll-defined area. But in statistical sciences by population we mean total number of individuals /objects /items having some common characteristics. Size of the population is represented by N. A population may be finite or infinite. A population is said to finite if its countable e.g. total number of students of FCC Lahore , Number of patients admitted at Jinnah hospital in September 2010, Number of car accidents in 2009 etc .Similarly, a population is said to be infinite if it is uncountable, e.g. population of throws of a die, population of stars on the sky etc. Sample: A small part of population which is selected randomly and it holds the characteristic of the respective population is called sample. Size of the sample is represented by n. Suppose ,a Statistics class consists of 40 students and we are interested to select 10 students randomly to get some kind of information. In this example 40 students is the size of population i.e. N=40 and 10 students chosen at random is the size of the sample i.e. n=10. Parameter and Statistic: Any numerical quantity such as an average, measure of variability etc. computed from population is called a parameter while any numerical quantity such as an average, measure of variability etc. computed from sample is called statistic.
- 3. Parameter is a fixed value, while statistic is a variable quantity and it changes from one sample to another. Parameters are usually denoted by Greek letters such as α, β, γ etc., while statistics are usually denoted by English letter such as a, b, c etc. Types of Statistics Descriptive Statistics: Methods of organizing, summarizing and presenting data in an informative way. Presenting the numerical information in the form of number, graphs and tables. Inferential Statistics: A decision, estimate, prediction, or generalization about a population, based on a sample. To estimate the population parameter on the basis of the sample statistic. Bio statistics The use of statistical methods in biological sciences is called biometry or Biostatistics. Variable and Constant:
- 4. A quantity which varies from one individual/object/unit to another individual/object/unit is called a variable. While a quantity which does not vary from one individual/object/unit to another individual/object/unit is called a constant. Variables are denoted by capital letters X ,Y, Z etc. ,while constants are denoted by small letters a, b, c etc .A variable can assume many values. A set of all possible values of a variable is called its sample space. A constant contains only one value in its sample space. Examples: The age of a person is a variable, as it varies from person to person. The height of an individual is a variable which changes from one individual to another. Number of noses and number of eyes of each person etc. are the examples of constants. Classification of Variables: Variables may be classified as quantitative and qualitative depending upon the characteristic of interest(See Figure).A variable is called a quantitative variable if the characteristic of interest can be expressed numerically such as age, height, weight ,blood pressure, income or number of children .On the other hand, a variable is called qualitative variable if the characteristic of interest cannot expressed numerically such as education, sex, eye color, intelligence, poverty etc. A qualitative variable is also called an attribute. A quantitative variable further more can be categorized as discrete and continuous variable.
- 5. Variable Qualitative Quantitative Discrete Continuous Discrete and Continuous Variables A variable that can take/ assume only integer type or fixed values is called discrete variable e.g. number of family members ,number of patients, shoe or shirt sizes. Similarly, a variable that can take/assume any value in an interval is called a continuous variable. Heights, weights, temperatures are examples of continuous variables. Collection of data The basic step in any investigation is collection of data. The data may be collected from the whole population or sample. But in most of cases data are collected through samples. The data collection is not an easy job. There must be some trained person/persons to do this job. Usually, the collected data are of two types. Primary Data: The data are called primary if it is collected originally by some individual/ department/agency. The primary data is free from any statistical operation/treatment. There are various methods to collect the primary data. For example: personal interviews, indirect personal investigation, questionnaires, local sources, enumerators. Secondary Data: the data is called secondary when the primary data has been treated by some statistical tool. If the primary data have been treated statistically it is no more primary. It becomes secondary data .The
- 6. secondary data are collected from individual units but are taken from different sources called secondary sources. Some of these sources are :Official statistics, Semiofficial, Newspapers, and Trade Journals. One or more of the following methods are employed to collect primary data: i) Direct Personal Investigation. ii) ii) Indirect Investigation. iii) Collection through Questionnaires iv) Collection through Enumerators v) Collection through Local Sources Application of Statistics in Pharmaceutical Sciences Statistics course in this department is taught in the context of the development of new pharmaceutical and biopharmaceutical products, with the goal of providing a solid knowledge and understanding of the nature, methods, applications, and importance of the discipline of Statistics. It should be emphasized that we are not training our students to be professional statisticians. Rather, we wish them to become familiar with the basics of design ,methodology ,and analysis as used in the development of new drugs. We aim to convey the following information: 1. why, and how, data are collected in clinical studies (to investigate a specific question, using appropriate study design and research methodology) 2. how these data are summarized and analyzed (descriptive statistics, hypothesis testing and inferential statistics, statistical significance)
- 7. 3. what the results mean in the context of the clinical research question (interpretation, estimation, and clinical significance) 4. how the results are communicated to regulatory agencies and to the scientific and medical communities.