 Hello friends, today we will be discussing on work sampling, we will have a small introduction of the work sampling, what is work sampling, what are its benefits and how to draw a work sampling chart and other things we will be able to discuss today. At the end of this session, we will be able to understand the concept of work sampling and the procedure to carry out the same. What is work sampling, what is principle, how to determine the sample size, what is the procedure, what are the advantages and limitations of this we are going to discuss today one by one. Initially start with what is work sampling, well it is a work measurement technique in which a large number of instantaneous observations are made at random intervals over a specified period of time of workers, machines and processes. As you know it is one of the measurement techniques, time study and work sampling are the true predominant measurement techniques where which are commonly used for finding out the time required for the job and then hence norm setting. Individually time study has its own areas of applications and work sampling has its own different area of applications, though both can be used to find out the time required for the particular operation. The work sampling is a basically a statistical technique where we have got large number of observations are to be made and what is the principle of work sampling, this is the principle of the work sampling. Work sampling it is a statistical technique based on the theory of sampling and probability. The distribution curve followed for the work sampling is generally normal distribution having a pattern of 6 sigma all of you know what is 6 sigma is and then we have to think of what are the various sigma levels and try to interpret the meaning of this. What is the meaning of 1 sigma, 2 sigma, 3 sigma plus minus 3 and plus minus 4 sigma each sigma will have a particular different area under the curve and it will represent a particular number that will be used hence forth for relevant calculations. So, we will be discussing much about these numbers and the sigma levels in the further part of this presentation. Sampling as you know is a basis of statistics and determination of sample size is a crucial matter in the sampling study. What is sampling? Now, for example, in the class the my class students have got a 80 percent attendance as an average. If I say that 80 percent average I am talking it on a sampling basis it does not mean that the same 20 percent students will remain absent continuously for all my lectures, but it depends upon the overall percentage of the absenteeism and present in students and if I take number of observations and try to find out the total percentage of students it comes out to be 80 percent. 20 percent of the floating population by and large will remain absent for the lecture that is what the sampling is. We also understand the sampling for election polls, we also have sampling for variety of economic surveys of the government, we also have sampling for students, their ages and their geographical studies. There are a number of statistical applications of the sampling where we are now try to find out sampling for utilization of the machine or sampling for utilization of equipment or manpower and in turn we are trying to find out utilization, then time required for a particular job and how to avoid the unnecessary doubt delay elements in the sampling asset. The sampling technique it relies on the sample size, the sample size formula is shown over here it is shown at x into sigma p which is equal to x under root p into bracket 1 minus p upon n where p is the average probability, x is the value which depends upon the desired confidence level, p is the percentage of occurrence of the activity, s is the error in the fraction and n number of observations required. As you know sampling will have major sampling dependency will have on the two major things the first is the number of samples to be taken that is sample size, the accuracy we are interested in and what is the confidence level of the particular accuracy these things are taken together. So, confidence level and the percentage error these are the two determinants which will determine the sampling size as such. Let us come back to the procedure of the work sampling how the procedure is we have to first define the problem what is the basic purpose of the problem as what is the basic purpose of the work sampling and why are going for this. Once the problem is well defined then we have to find design a chart which is usual for recording information then make a pilot study pilot study with some observations may be 100, 250 depends upon the feasibility depends upon the further accuracy we wanted and so on. Once the preliminary observations are done then we have to calculate the exact number of observations required for the designed confidence level and for the designed accuracy level. We may have to compute the delay percentage and then we have to determine the accuracy and confidence level as desired for the investigation. Once this is decided then we have to get these approvals from the section heads or the concerned management people we have to explain them what is the entire procedure and then we have to tell them what is the confidence level we are interested in what is the accuracy. Also workers, operators and the entire group has to be taken into confidence and to explain them what is the purpose of this study and what we are going to achieve through this purpose it is not a personal based technique generally operators will have a resistance initially they have got lot of myths about the particular any industry technique as such work sampling of course is not an exception to it we have to explain them very well what is the purpose why you are going to study and other things. Once that is there then we have to continue the number of observations required for the chosen confidence level it depends upon more number of observations more will be the accuracy with increased number of observations of course cost will also increase. Number of observations are decided in the light of confidence level required once the observations are final completed then we have to observations are decided we have to select and instruct the people we have to just give the instructions that how observations are to be taken what is it determine number of days or shifts required for the study plan the schedule of the observations such as time for taking and route to be followed by the observer with the sampling of observations in the chart making note of any unusual points once the data is available then presenting the results the work sampling data are analyzed during the study in order to check if the things are going according to the plan or not the data is usually summarized at the end of the each day the activities now after the procedure if you understand the procedure for example even if you take a very simple example that is there are only two machines just to understand I am just explaining the concept there are two machines are there and a one supervisor there who want to study the utilization of the machine what you will do is you will finalize a sampling study and take random observations of the machine and then calculate the total percentage of the observations of working and now working to the total number of observations and that will give the proper utilization what are the advantages of this the activities are impractical or costly to measure can be measured readily by work sampling a single observer can make all the study as compared to that required for continuous time study the cost and time involved in the work sampling study is quite less as compared to other data other techniques work sampling study may be interpreted at any time without affecting the results there is less chance of obtaining misleading results as the operators are not under close observation work sampling studies are less tedious and cause less fatigue to the observer it is not necessary to use trained a time study observer time study is a very very skilled job time study requires lot of training to the time study engineer you have to have a lot of issues in the time study and only trained a time study people can take it whereas work sampling just is only take random observations at a given moment and mark in the appropriate column whether it is working non-working or delay and what is the reason for the lay there's just a simple a simple typical job which you have to follow the instructions once that is there and stopwatch or other time devices are not required for work sampling the only major thing is it requires the random sampling and the random numbers are generated using by random number tables or calculator or computers nowadays we can use random numbers and then we have to follow the random numbers take the observations well there are some limitations of this study the limitations are it does not permit finer breakdown of the activities and delays it cannot provide a detailed information it is economical when a large number of operators are observed for studying operators or machines located over wide areas in certain kind of work sampling studies the record of method used by the operator is not made therefore whenever a method change occurs any element in the entire new study must be made it is not a record specific we are not recording any method during the work sampling as such management or workers may not understand statistical work sampling as they to time study time study though it is difficult to conduct analyze but is that way easily understood by the workers as well as the management but whereas work sampling being a statistical one they may feel that it was lot of statistical jargon as a result of that it is slightly difficult to make them convinced to the workers and management that what are the various applications what are the various analysis and conclusions of the work sampling and what are the advantages of it so there are some natural limitations of this work sampling as such so in summary we have studied today what is work sampling what are its applications and how to go about work sampling what are the procedure what is step by step element and how to follow the work sampling process well let us try with this procedure and you can try one actual work sampling study under your observations by visiting to here by industry thank you