April 9, 2022

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT401 PROBABILITY AND STATISTICS DATE: AUGUST, 2017 TIME: 1 ½ HOURS INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions. QUESTION ONE a) Differentiate between the following terms as used in statistics i. Qualitative and quantitative variables ii. Population and sample iii. Discrete and continuous variables (9 Marks) b) The number of points scored in each game by a college team were recorded as follows. Points scored Matches Calculate i. Mean (3 Marks) ii. Mean absolute deviation (3 Marks) iii. Variance (3 Marks) iv. Standard deviation (3 Marks) c) A certain data set was collected on a random variable x and the following summaries made: = 260 and = 2670 Find i. The mean (4 Marks) ii. The standard deviation (4 Marks) QUESTION TWO a) Find the correlation coefficient by karlpearson’s method between x and y and interpret its value (4 Marks) b) Births in a hospital occur randomly at an average rate of 1.8 births per hour. What is the probability of observing 4 births in a given hour at the hospital? (4 Marks) c) The table below gives the probability distribution of a discrete random variable x. Given that p(x<13) = 0.75, find the value of k and q hence calculate e(x) (4 Marks) d) The probability that i hit a target is , and the probability that b hits the target is . Both shoot at the target. Find the probability that (i) At least one of them hits the target. (3 Marks) (ii) Neither hits the target (2 Marks) e) The probability that a student owns a computer is 0.65 and the probability that a student owns a phone is 0.82. If the probability that a student owns both is 0.55. What is the probability that a given student owns either a phone or a computer (3 Marks) X 4 8 12 15 20 P(x) k 0.25 0.3 q 0.1 QUESTION THREE a) In a class with 10 girls and 20 boys, the following are to be randomly chosen class officials; class spokesperson and class welfare officer. What is the probability that the two of the officials are girls? (2 Marks) b) The weight of 8 diploma students were taken in variable x as they reported and the following results calculated. (6 Marks) ∑ x = 440 and ∑x2 = 24592 Calculate i) The mean (3 Marks) ii) The Variance (3 Marks) iii) The standard deviation (3 Marks) c) A class has 10 boys and 5 girls, three students are selected at random. Using a tree diagram, find the probability that: i) All are girls (3 Marks) ii) First 2 are boys (3 Marks) iii) First and third are of the same sex and the second of opposite sex (3 Marks) QUESTION FOUR a) In a study of the daily production of a company over 50 days, the following data was obtained b) Using a suitable assumed mean, calculate the mean and standard deviation of this data. (14 Marks) c) In a bag of 40 vegetables, 25 are carrots and 15 are potatoes. The mean weight of the carrots is 60grams while that of the potatoes is 52 grams. The standard deviations of the weights arc 4 grams and 6 grams for the carrots and potatoes, respectively. Calculate the mean and standard deviation of all the vegetables in the bag. (6 Marks) 65 76 36 48 49 48 84 55 79 51 43 21 78 35 37 61 40 45 68 34 88 45 50 53 60 34 56 67 57 42 59 62 62 65 76 55 74 61 70 73 35 41 60 74 52 82 63 58 32 26 QUESTION FIVE a) The following is data on the heights, in meters, of trees in a certain forest 31 51 37 41 68 50 32 60 53 45 64 54 53 83 52 55 73 55 66 75 57 59 48 70 71 40 53 47 48 36 45 34 26 72 25 29 18 43 48 26 72 15 36 27 39 50 69 32 Prepare a grouped frequency distribution and find the mean of the grouped data ( 15 Marks) b) In a company there are 10 managers and 6 accountants. 6 managers and 3 accountants are female, find the probability that a person selected at random is a. (5 Marks)

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT305 PROGRAMMING METHODOLOGY MODE: FULL TIME/PART TIME ORDINARY EXAMINATIONS DATE: AUGUST, 2017 DURATION: 2 HOURS INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions. QUESTION ONE [30 MARKS] – COMPULSORY a) Briefly explain the problem-solving steps with respect to programming. [6 Marks] b) Differentiate between debugging and profiling as used program testing. [4 Marks] c) Differentiate between compiled programming language and interpreted programming language. [4 Marks] d) Briefly explain the use of a pre-processor in programming. [2 Marks] e) Design a program using a flow chart to prompt the user to enter a score, then return a grade based on the following criteria. [10 Marks] f) Discuss the four calculation operations in C. [4 Marks] QUESTION TWO [20 MARKS] a) Briefly describe four properties of a good program. [4 Marks] b) Briefly outline three types of information provided whenever a variable is declared in C. [3 Marks] c) Differentiate between a fatal and non-fatal error in a program. Give one example for each. [4 Marks] d) It is recommended that programmers should indent program statements properly, explain why this necessary. [3 Marks] e) Write a C program to prompt the user to enter his user name and password then validate the values and return the appropriate message using the criteria below. [6 Marks] QUESTION THREE [20 MARKS] a) Briefly describe the three program control structures in structured programming. [6 Marks] b) Briefly explain the difference between a do while loop and a while loop. [4 Marks] c) Describe the difference between break and continue statements in a loop. [4 Marks] d) Write a C program to print odd numbers greater than 0 but less than 100. [6 Marks] QUESTION FOUR [20 MARKS] a) Discuss the following user defined data types in C i. Enumeration ii. Typedef iii. Union iv. Array [8 Marks] b) Write a C program to store twenty floating numbers in an array, then display them in reverse order. [4 Marks] c) Explain the difference between order of precedence and associativity with respect to operators in C. [2 Marks] d) Explain the output of the following statements in C. Assume x=100 and y=23 that use bitwise operators. i. printf (“%d \n”, x>>2); ii. printf (“%d \n”, y<<2); iii. printf (“%d \n”, x&y); [6 Marks] QUESTION FIVE [20 MARKS] a) Briefly explain three advantages of modularization in C. [3 Marks] b) Write a C program to prompt the user to key in a natural number, then calculate and display its factorial. [5 Marks] c) Explain the user of formal parameters in a function. [4 Marks] d) A C program function be user defined or built-in. Explain the use of the following built-in functions in C. a. printf () i. strcat () ii. pow () iii. sqrt () [8 Marks]

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT204 DISCRETE MATHEMATICS DATE: AUGUST, 2017 TIME: 1 ½ HOURS INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions. QUESTION ONE a) Briefly explain your understanding of discrete mathematics as contrasted with other branches of mathematics (4 Marks) r “a” belongs to the set of the English alphabet vowels, V. Express that statement u b) The lette sing an appropriate mathematical symbol (4 Marks) c) A sample of 55 secondary school students was surveyed to determine some KNEC registration statistics. Of those sampled, the registration numbers were as follows: 25,19 and 22 students registered for Geography, Chemistry and Biology respectively; 10 registered for Chemistry and Geography, 9 registered for Chemistry and Geography; 7 registered for Geography and Biology whereas 4 registered for all the three subjects. I. Represent the above information on a Venn diagram (4 Marks) II. From the Venn diagram in (i) above, determine (4 Marks) i. The number of students that registered for only one of the three subjects (4 Marks) ii. The percentage of students that registered for none of the three subjects (4 Marks) QUESTION TWO a) Define a proposition and state any three valid propositions (3 Marks) b) Define with help of truth tables and proposition p and q: i. A conjunction (3 Marks) ii. A disjunction (3 Marks) iii. Negative of proposition q (3 Marks) c) With the help of a truth table, show that a contradiction (4 Marks) d) Define the following terms as used in graph theory: i. A directed graph (2 Marks) ii. A multigraph (2 Marks) QUESTION THREE a) Define a function as used in mathematics b) Distinguish between the domain and the range of a function ( Hint: use sets A and B ) c) State the difference(s) between a relation and a function. d) Given two sets: A= {a, b, c, d, e} and B = {1, 2, 3, 4, 5, 6}. State, with reasons, whether the following are functions or not. i. f = { (a,2), (b,3), (c,9), (d,3), (e,4)} (3 Marks) ii. g = { (b,2), (a,3), (c,4), (d,5), (a,6)} (3 Marks) iii. h = { (b,2), (c,2), (a,2), (d,2), (e,2)} (3 Marks) e) Differentiate, with examples, amongst, Injectives Bijectives and Surjectives (4 Marks) f) Let A = (5, 6, 7, 8), B = (q, r, s, t) and C= (w, x, y). If f is the function: f: A→ B and g: B→ C defined by : f = {(5, s), (6, t), (7, r) (8, r)} g = {(q, w), (s, x), (r, y), (t, w)} Find the composition function f◦g

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT203 SYSTEMS ANALYSIS AND DESIGN DATE: AUGUST, 2017 TIME: 2 HOURS INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions. QUESTION ONE [30 MARKS] – COMPULSORY a) For one to create an entity relationship diagram, there are best practice to be followed. State and explain any five (10 Marks) b) Describe any four characteristics of a general system. (8 Marks) c) What is the importance of the skills that a system analyst possess? [6 Marks] d) Explain why you think the use of CASE Tools may lead to high quality system documentation (6 Marks) QUESTION TWO [20 MARKS] a) For a student to be admitted to KCA University there are several processes that he or she must follow. The student must have applied for a course he is going to undertake and received an admission letter containing some forms which the student is supposed to fill. On the day of admission, the student is supposed to come with the admission letter and the filled forms, the forms include an acceptance letter, details letter, parents or guardian details, residence details and medical report. The student is also required to come with his original result slip or certificates and identification documents. The student normally starts his admission process at the school he has been called. The administrator of that school will be responsible of the verification of all the documents and admit the student in to the university. Using a data flow diagram, demonstrate the above admission process. (10 Marks) Page 2 of 2 b) Explain advantages of prototyping as a system implementation methodology. (5 Marks) c) Describe the steps followed in a waterfall model. (5 Marks) QUESTION THREE [20 MARKS] a) Describe FOUR different ways in which the changeover to a new system can take place. Highlight the advantages of EACH. (8 Marks) b) Explain any four method of collecting data during system analysis that you will make use of when involved in a system analysis process clearly stating their advantages and disadvantages. (8 Marks) c) Define the following terms as used in Entity relationship diagrams (4 Marks) i) Relationships ii) Cardinality QUESTION FOUR [20 MARKS] a) What are the advantages of using structured methodology in relation to traditional approaches? (8 Marks) b) Outline the category of end user tests that may be adopted before the full release of a computerized information system. (6 Marks) c) State and Explain FOUR information systems components (8 Marks) QUESTION FIVE [20 MARKS] a) Clearly define the different activities that are carried out in the system analysis and design process (8 Marks) b) What is the difference between output and input as used in system analysis and design? (4 Marks) c) Differentiate between cybernetic systems and deterministic systems (4 Marks) d) Why is it important for documentation when implementing a new system? (4 Marks)

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY/ DIPLOMA IN BUSINESS INFORMATION TECHNOLOGY DIT0200 DCU 201 COMPUTER APPLICATION SOFTWARE DATE: AUGUST, 2017 TIME: 2 HOURS INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions. QUESTION ONE [30 MARKS] – COMPULSORY a) Explain the following terms as used in spreadsheet application. i. Cell ii. Workbook iii. Range iv. Name box v. Formula bar [5 Marks] b) Differentiate Hard and soft copy. [2 Marks] c) Explain FOUR advantages of Office Automation Systems [4 Marks] d) Explain FIVE reasons why computers are considered to be useful in business organizations. [5 Marks] e) Explain FOUR views that you normally use from time to time when one is working with power point application [4 Marks] f) Explain FIVE computer Application areas. [10 Marks] QUESTION TWO [20 MARKS] a) List any FOUR database management application software [4 Marks] b) Explain FIVE types of charts that can be created in Ms excel application [5 Marks] c) Explain any THREE computer networking devices [6 Marks] d) Explain FIVE use of power point presentation in the current times. [5 marks] QUESTION THREE [20 MARKS] a) Define the term text-box as used in word processing [2 Marks] b) List SIX Characteristics of an integrated software [6 Marks] c) Explain FOUR features of the fourth computer programming languages [6 Marks] d) Briefly, explain the following database terms, giving examples where appropriate i. Primary Key ii. Foreign Key iii. Domain iv. Data-type v. Field vi. Junction Table [6 Marks] QUESTION FOUR [20 MARKS] a) Using examples differentiate between table and query as used in Ms Access database application software. [6 Marks] b) Peter has bought a computer with the following software: Word Processing, Spreadsheets, Database, Computerized Accounting and Graphics modules. State the purpose of each module. [5 Marks] c) The computer had a CD-ROM drive. State clearly TWO differences between CD-ROM and a Flash Disk. [4 Marks] d) Explain FIVE input devices the student can use to play games. [5 marks] QUESTION FIVE [20 MARKS] a) Explain how the following tasks can be executed in Ms-Excel i. Adding numbers in a range [1 Mark] ii. Calculating the monthly loan repayment for a loan. Suggest the principal, time and rate [2 Marks] iii. Calculate for mean value of numbers [1 Mark] iv. Count occupied cell in a range [1 Mark] b) Outline FOUR benefits of computer network to the organization. [4 Marks] c) Explain SIX data types you may use in a Microsoft Access table [6 Marks] d) Explain the function of the following features/tools in word Processing i. Replace ii. Frames iii. Show/hide icon iv. Mailing [4 Marks]

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT107 MATHEMATICS FOR SCIENCE DATE: AUGUST, 2017 TIME: 2 HOURS INSTRUCTIONS: Answer Question One and any other TWO questions. QUESTION ONE a) State the most important characteristic of quadratic functions (2 Marks) b) State any four methods for solving quadratic equations (4 Marks) c) By using an appropriate formula, determine the roots to the quadratic equations QUESTION TWO a) Distinguish between a sequence and a series (4Marks) b) Given the series 3 + 8 + 13 + . . . Determine i) The first term, a (4Marks) ii) The common difference,d (4Marks) iii) The 42nd term (4Marks) iv) The sum to the 30th term (4Marks) QUESTION THREE a) Simplify the following indices without using a calculator QUESTION FOUR a) Express each of their following in their simplest forms possible QUESTIONFIVE a) If log10 = 0.3010 and log103 = 0.4771, find without using a calculator or mathematical tables correct to 4 decimal places the values of i. log10 18 (4Marks) ii. log10 1.5 (4Marks) b) Using the long division method, find the remainder when the function c) Using the remainder theorem, confirm your solution in b (i) above. (5 Marks) d) From your result in (d) above, state whether (x + 2) in a factor of f (x)

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY/DIPLOMA IN BUSINESS INFORMATION TECHNOLOGY DIT105 DBIT104 COMPUTER APPLICATION SOFTWARE DATE: AUGUST, 2017 TIME: 2 HOURS INSTRUCTIONS: Answer question ONE and any other TWO questions. QUESTION ONE (30 MARKS) – COMPULSORY a) Automating organizations activities using computers brings about efficiency and effectiveness. In light of this: i. Outline five advantages of using computers (5 Marks) ii. Outline five disadvantages of using computers (5 Marks) iii. Explain five factors you would look for when purchasing an application software. (5 Marks) b) Explain the five computer generations outlining how they evolved as far as processing is concerned. (5 Marks) c) Explain five views as used in ms-word application. (5 Marks) d) Differentiate between the following terms. (5 Marks) i. Header & Footer ii. Editing & Formatting iii. Ms-excel & Ms- PowerPoint iv. Superscript & Subscript v. Alignment and Margin QUESTION TWO (20 MARKS) a) Name 5 characteristics of a computer (5 Marks) b) Convert the following binary numbers to decimal (5 Marks) i. 11111 ii.111011 iii.0.1111 iv. 00001111 v.111111 c) Explain how you would carry out the following operations (4 Marks) i. Open an existing document ii. Create a new document d) Discuss SIX computer application areas (6 Marks) e) Convert the following Octal numbers to binary (5 Marks) i. 454 ii. 657 iii. 555.56 iv.236 v. 743 QUESTION THREE (20 MARKS) a) XYZ Company intends to computerize its operations but before they do that the management is carrying out a research to see whether the benefits of this change outweigh the costs. You happen to be one of the respondents in the department where this research is being carried out. Outline any five reasons the company employees would resist this move. (5 Marks) b) Explain the four classifications of computers (8 Marks) c) Differentiate data from information (2 Marks) d) Explain FIVE classifications of computer Hardware. (5 Marks) QUESTION FOUR (20 MARKS) a) With the aid of a well labelled diagram explain the computer system architecture (10 Marks) b) What is computer Hardware? (2 Marks) c) Name two internet browsers (2 Marks) d) Write the following abbreviations in full and indicate their capacities (3 Marks) i. KB ii. MB iii. GB e) Explain what you understand by the term Operating System and give an example. (3 Marks) QUESTION FIVE (20 MARKS) a) Briefly explain what you understand by RAM and ROM (4 Marks) b) Semi-conductor memories gained popularity over the core memories give reasons for this. (4 Marks) c) What is systems software? Name the three categories of system software (5 Marks) d) Explain any FIVE crimes committed using computers. (5 Marks) e) Name the four basic number systems in use today (2 Marks)

The economic advantages of taking a sample rather than a census are massive. Consider the cost of taking a census. 1. Why should we spend thousands of shillings interviewing all 4,000 employees in our company if we can find out what we need to know by asking only a few hundred? 2. Deming argues that the quality of a study is often better with sampling than with a census. He suggests, ‗Sampling possesses the possibility of better interviewing (testing), more thorough investigation of missing, wrong, or suspicious information. Research findings substantiate this opinion. 3. Sampling also provides much quicker results than does a census. The speed of execution reduces the time between the recognition of a need for information and the availability of that information. 4. Some situations require sampling. When we test the breaking strength of materials, we must destroy them; a census would mean complete destruction of all materials. Sampling is also the only process possible if the population is infinite. 5. In few cases, it would be impossible or dangerous to use whole population, i.e., testing of vaccine for AIDs – could result in death. The advantages of sampling over census studies are less compelling when the population is small and the variability is high. Two conditions are appropriate for a census study: A census is 1. Feasible when the population is small and 2. Necessary when the elements are quite different from each other. When the population is small and variable, any sample we draw may not be representative of the population from which it is drawn. The resulting values we calculate from the sample are Incorrect as estimates of the population values. When the sample is drawn properly, however, some sample elements underestimate the parameters and others overestimate them. Variations in these values counteract each other, this counteraction results in a sample value that is generally close to the population value. For these offsetting effects to occur, however, there must be enough members in the sample, and they must be drawn in a way to favour neither overestimation nor underestimation.

UNIVERSITY EXAMINATIONS: 2016/2017 EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT104 COMPUTER ORGANIZATION AND APPLICATION SPECIAL/SUPPLEMENTARY EXAMINATION DATE: JULY, 2017 TIME: 2 HOURS INSTRUCTIONS: Answer any THREE questions. QUESTION ONE a) Explain how the following tasks can be executed in Ms-Excel. (i) Adding numbers in a range [1 Mark] (ii) Calculating the monthly loan repayment for a loan. Suggest the principal, time and rate. [2 Marks] (iii)Calculate for mean value of numbers [1 Mark] (iv)Count occupied cell in a range [1 Mark] b) Outline FIVE benefits of computer network to the organization. [5 Marks] c) Explain SIX data types you may use in a Microsoft Access table. [6 Marks] d) Explain the function of the following features/tools in word Processing. (i) Replace (ii) Frames (iii)Show/hide icon (iv)Mailing [4 Marks] QUESTION TWO a) Using examples differentiate between table and query as used in Ms Access database application software. [6 Marks] b) Peter has bought a computer with the following software: Word Processing, Spreadsheets, Database, Computerized Accounting and Graphics modules. State the purpose of each module. [5 Marks] c) The computer had a CD-ROM drive. State clearly TWO differences between CD-ROM and a Flash Disk. [4 Marks] d) Explain FIVE input devices the student can use to play games. [5 Marks] QUESTION THREE a) Define the term text-box as used in word processing. [2 Marks] b) List SIX Characteristics of an integrated software. [6 Marks] c) Differentiate between High level language and low level language in computing world? [4 Marks] d) Explain any FOUR different types of computer software. [4 Marks] e) Differentiate between input and output devices giving examples in each scenarios. [4 Marks] QUESTION FOUR a) List any FOUR database management application software. [4 Marks] b) Explain FIVE types of charts that can be created in Ms excel application. [5 Marks] c) Explain any THREE computer networking devices. [6 Marks] d) Explain FIVE use of power point presentation in the current times. [5 Marks] QUESTION FIVE a) Explain FOUR types of computer classifications giving examples in each scenarios. [8 Marks] b) Differentiate Hard and soft copy. [2 Marks] c) Explain FOUR advantages of Office Automation Systems. [4 Marks] d) Explain TWO reasons why computers are considered to be useful in business organizations. [2 Marks] e) Explain FOUR views that you normally use from time to time when one is working with power point application. [4 Marks]

UNIVERSITY EXAMINATIONS: 2016/2017 ORDINARY EXAMINATION FOR THE DIPLOMA IN INFORMATION TECHNOLOGY DIT 505 WEB DESIGN DEVELOPMENT DATE: AUGUST, 2017 TIME: 2 HOURS INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions. QUESTION ONE [30 MARKS] – COMPULSORY a) Define the following terms and acronyms as used in web design [10Marks] i. HTTP ii. WWW iii. CSS iv. tag v. attribute vi. HTML vii. attribute value viii. webpage ix. website x. blog b) List two advantages and two disadvantages the Web [4Marks] c) Briefly describe the following types of websites [6Marks] i. Personal ii. brochure iii. information d) Give the function of the following tags [5Marks] i. <table> ii. <u> iii. <li> iv. <p> v. <em> vi. <hr /> vii. <input> viii.<br> ix. <dl> x. <th> e) Give the effect of the following attributes. Also indicate where they are used [5Marks] i. id=“bottom_of_page” ii. width=“80%” iii. color=“#00ff00” iv. valign=“middle” v. size=“15” QUESTION TWO [20 MARKS] a) Create a Form with the following output [10 Marks] b) Write a JavaScript code to find the multiple of two numbers. [6 Marks] c) Differentiate between Domain name and Domain name system [4 Marks] QUESTION THREE [20 MARKS] a) Explain the website maintenance process [5 Marks] b) Give the html element that displays an image kcalogo.png at the top of a web page [4 Marks] c) Using examples, differentiate between fixed layout and fluid layout [5 Marks] d) Give html elements for linking html page to an external image. [4 Marks] e) Give the difference between an absolute link and a relative link [2 Marks] QUESTION FOUR [20 MARKS] a) Using relevant examples differentiate between <body> and <title>tag. [6 Marks] b) What are the key visual tools used to create an effective web design? [4 Marks] c) What are the services offered under web design and web development? [6 Marks] d) Differentiate between ordered list and give an example for each [4 Marks] QUESTION FIVE [20 MARKS] a) Define JavaScript Function using an Example. [6 Marks] c) Differentiate between logical tags and physical tags giving an example of each [4 Marks] c) Write an HTML code to display the following output? [10 Marks]

The researcher must identify the target population and select the sample if a census is not desired. The researcher then determines how many people to interview and who they will be; what and how many events to observe; how many records to inspect and which ones. Once the population of interest is determined, the researcher has to decide whether data will be collected from all study units or from some of the units in the population. A sample is a part or a portion of the target population carefully selected to represent that population. When researchers undertake sampling studies, they are interested in estimating one or more population values and or testing one or more statistical hypothesis. The sampling process must give every person within a target population a known nonzero chance of selection if probability sampling is used. If there is no feasible alternative, a non-profitability approach may be used. The basic idea of sampling is that by selecting some of the elements in a population, we may draw conclusions about the entire population. A population element is the subject on which the measurement is being taken. It is the unit of study. A population is the total collection of elements about which we wish to make some inferences. A census is a count of all the elements in a population

Professor Fisher has enumerated three principles of experimental designs: (1) the Principle of Replication; (2) the Principle of Randomization; and the (3) Principle of Local Control. According to the Principle of Replication, the experiment should be repeated more than once. Thus, each treatment is applied in many experimental units instead of one. By doing so the statistical accuracy of the experiments is increased. For example, suppose we are to examine the effect of two varieties of rice. For this purpose we may divide the field into two parts and grow one variety in one part and the other variety in the other part. We can then compare the yield of the two parts and draw conclusion on that basis. But if we are to apply the principle of replication to this experiment, then we first divide the field into several parts, grow one variety in half of these parts and the other variety in the remaining parts. We can then collect the data of yield of the two varieties and draw conclusion by comparing the same. The result so obtained will be more reliable in comparison to the conclusion we draw without applying the principle of replication. The entire experiment can even be repeated several times for better results. Conceptually replication does not present any difficulty, but computationally it does. For example, if an experiment requiring a two-way analysis of variance is replicated, it will then require a three-way analysis of variance since replication itself may be a source of variation in the data. However, it should be remembered that replication is introduced in order to increase the precision of a study; that is to say, to increase the accuracy with which the main effects and interactions can be estimated. The Principle of Randomization provides protection, when we conduct an experiment, against the effect of extraneous factors by randomization. In other words, this principle indicates that we should design or plan the experiment in such a way that the variations caused by extraneous factors can all be combined under the general heading of ―chance.‖ For instance, if we grow one variety of rice, say, in the first half of the parts of a field and the other variety is grown in the other half, then it is just possible that the soil fertility may be different in the first half in comparison to the other half. If this is so, our results would not be realistic. In such a situation, we may assign the variety of rice to be grown in different parts of the field on the basis of some random sampling technique i.e., we may apply randomization principle and protect ourselves against the effects of the extraneous factors (soil fertility differences in the given case). As such, through the application of the principle of randomization, we can have a better estimate of the experimental error. The Principle of Local Control is another important principle of experimental designs. Under it the extraneous factor, the known source of variability, is made to vary deliberately over as wide a range as necessary and this needs to be done in such a way that the variability it causes can be measured and hence eliminated from the experimental error. This means that we should plan the experiment in a manner that we can perform a two-way analysis of variance, in which the total variability of the data is divided into three components attributed to treatments (varieties of rice in our case), the extraneous factor (soil fertility in our case) and experimental error. In other words, according to the principle of local control, we first divide the field into several homogeneous parts, known as blocks, and then each such block is divided into parts equal to the number of treatments. Then the treatments are randomly assigned to these parts of a block. Dividing the field into several homogenous parts is known as ‗blocking‘. In general, blocks are the levels at which we hold an extraneous factor fixed, so that we can measure its contribution to the total variability of the data by means of a two-way analysis of variance. In brief, through the principle of local control we can eliminate the variability due to extraneous factor(s) from the experimental error.