Total sample size k i i nn population n units stratum 1. Stratified sampling a method of probability sampling where all members of the population have an equal chance of being included population is divided into strata sub populations and random samples are drawn from each. In stratified random sampling or stratification, the strata. Aug 27, 2012 the corbettmaths video tutorial on stratified sampling. Final members for research are randomly chosen from the various strata which leads to cost reduction and improved response efficiency. The student will demonstrate the simple random, systematic, stratified, and cluster sampling techniques. By separating the population into groups age groups, genders, etc. This sampling method is also called random quota sampling. Which type of random sample is used for selecting a sample from one strata of society. Chapter 1 sampling and experimental design read sections 1. Jenny is carrying out a survey for her gcse mathematics project. Jan 05, 2012 a worksheet and exam style practice questions covering gcse stratified sampling. Stratified random sample the population is divided into subgroups for example, by gender, age or nationality and a.
Systematic random sampling is used to interview residents in 25% of 80 apartments in a building. So whether youre looking to help your child with stratified sampling or to guide your pupils through biased questions, our worksheets will help them with all they. All the sampling units drawn from each stratum will constitute a stratified sample of size 1. Work out the number of students in the sample who are male and in the lower sixth. For instance, if your four strata contain 200, 400, 600, and 800 people, you may choose to have different sampling fractions for each stratum. Use the worksheet and quiz to identify study points to watch for. Random and stratified sampling this lesson can be used for revision for the higher maths gcse. This is a whole lesson looking at stratified sampling and random sampling as a whole. The number of samples selected from each stratum is proportional to the size, variation, as well as the cost c i of sampling in each stratum.
Create your account to access this entire worksheet a premium account gives you access to all lesson. Random and stratified sampling questions, worksheets, videos. Stratified random sampling is a method of sampling that involves the division of a population into smaller groups known as strata. Every fifth person boarding a plane is searched thoroughly. Bias in survey sampling in survey sampling, bias refers to the tendency of a sample statistic to systematically over or underestimate a population parameter. Sample surveys, be they general population surveys or surveys of specific populations, can take many different. A simple random sample is used to represent the entire data population. It is useful when the researcher know little about a group or organisation. Stratified random sampling definition investopedia.
Apr 19, 2019 simple random samples and stratified random samples are both statistical measurement tools. Lesson includes definition and builds the difficulty of examples which my class found insightful. Number of sampling units to be drawn from ith stratum. Sampling experiment worksheet statistics libretexts. In this worksheet, we will practice simple random sampling, stratified sampling, and cluster sampling. Performing an effective survey and interpreting the data is a skill which students will come across in real life, so prepare them well with the sampling methods resources we have available at cazoom maths. Sampling methods answers identify the sampling method. We are working hard on a new platform for setting, building and monitoring homework. Random and stratified sampling questions, worksheets. Systematic sampling, stratified sampling, cluster sampling, multistage sampling. Jan 10, 2020 the student will demonstrate the simple random, systematic, stratified, and cluster sampling techniques.
Each student studies one of greek or spanish or german or french. Stratified cluster simple random systematic stratified cluster simple random apr 219. Cluster sampling allows groups to mix together, but stratified random sampling does not. At a local community college, five math classes are randomly selected out of 20 and all of the students from each class are. A manual for selecting sampling techniques in research 4 preface the manual for sampling techniques used in social sciences is an effort to describe various types of sampling methodologies that are used in researches of social sciences in an easy and understandable way.
Printable samples and surveys worksheets with answers our worksheets help kids master the art of surveys and sampling. She uses a stratified sample of 60 students according to year group. Math 145 elementary statistics sampling worksheet i. Freedman department of statistics university of california berkeley, ca 94720 the basic idea in sampling is extrapolation from the part to the wholefrom the sample to the population. Understanding stratified samples and how to make them. Stratified sampling is a probability sampling procedure in which the target population is first separated into mutually exclusive, homogeneous segments strata, and then a simple random sample is selected from each segment stratum. Stratified sampling is a probability sampling method and a form of random sampling in which the population is divided into two or more groups strata according to one or more common attributes stratified random sampling intends to guarantee that the sample represents specific subgroups or strata. Stratified sampling worksheet and exam practice qs teaching. A sampling frame is a list of the actual cases from which sample will be drawn. Simple random sample each member of the population has an equal chance of being selected. This quiz worksheet pairing will assess your knowledge of sampling techniques in scientific investigations. Do not know in advance how likely that any element of the population will be selected for the sample.
Every member of the population is equally likely to be selected. In a stratified sample, the proportion of each group is the same as the proportion in the whole population. Number of sampling units in ith strata 1 k i i nn ni. There are a number of different ways to choose a sample. The population is sometimes rather mysteriously called the universe. They are also usually the easiest designs to implement. The examples are quick and concise with exam style questions, go to gcse maths if you need more indepth explanations. The main part of the lesson is looking at how to calculate a stratified sample but it does include a great video on random sampling and how to use a calculator to do so. Stratified sampling practice questions corbettmaths. Review your knowledge of stratified random samples and how they are obtained. It is an easy to use stratified sampling calculator which only requires minum data input. Every element in the population has a none nonzero probability of being selected.
Sampling theory chapter 4 stratified sampling shalabh, iit kanpur page 2 notations. Samples are then pulled from these strata, and analysis is performed to make inferences about the greater population of interest. Stratified sampling questions worksheets and revision mme. Mathematics linear 1ma0 stratified sampling materials required for examination items included with question papers ruler graduated in centimetres and nil millimetres, protractor, compasses, pen, hb pencil, eraser. The student will explain the details of each procedure used. Stratified random sampling the way in which was have selected sample units thus far has required us to know little about the population of interest in advance of selecting the sample. Sample for each category selected randomly from the population age group population 000s sample male female total male female total 04 830 772 1602 41 38 79 59 1005 945 1950 50 47 97 1014 1016 958 1974 51 48 99. An example will help understand stratified sampling better. Dfm is a huge bank of free educational resources for teaching mathematics, with full sets of slides, worksheets, games and assessments that span year 7 to further maths and enrichment resources with a maths challengeolympiad focus. Stratified random sampling allows us to ensure a certain percentage of important subgroups e.
Is sampling with probability proportional to size pps a variant of cluster sampling. Simple random sampling in an ordered systematic way, e. This is a website which cointains a stratified sampling calculator to save you time from having to do the maths. The examples are quick and concise with exam style questions, go to gcse maths if. Stratified sampling is a probability sampling method and a form of random sampling in which the population is divided into two or more groups strata according to one or more common attributes. Maths made easy gives you access to maths worksheets, practice questions and videos to help you revise. Before we go further however, we should know the following 4 definitions. The stratified sampling calculator was developed by jacob cons. Sampling theory chapter 4 stratified sampling shalabh, iit kanpur page 7 3. Stratified sampling is a method we can use to make our sample more representative. Previous rounding highest lowest practice questions. An inspector wants to look at the work of a stratified.
Bias due to unrepresentative samples a good sample is representative. Population divided into different groups from which we sample randomly. Stratified random sampling is a method of sampling that involves the division of a population into smaller subgroups known as strata. Stratified random sampling intends to guarantee that the sample represents specific subgroups or strata. Bias and sampling worksheet multiple choice identify the choice that best completes the statement or answers the question. He wants to find out how often people have been to the library in the last year.
Administrative convenience can be exercised in stratified sampling. Discrete data or discrete variables can only take certain values, e. At a local community college, five math classes are randomly selected out of 20 and all of the. Simple random sampling and systematic sampling simple random sampling and systematic sampling provide the foundation for almost all of the more complex sampling designs based on probability sampling. Sampling method 3 if we are most interested in comparing scores of boys versus girls, we need to ensure our sample includes sufficient numbers of each. The main part of the lesson is looking at how to calculate a stratified. A manual for selecting sampling techniques in research. Estimation of population mean under stratified random sampling note that the population mean is given by x h l h h h l h n i hi l h w x n x h. For the quiz, you will need to know topics that include stratified and cluster sampling. Covers all parts of the gcse syllabus, including sampling methods random and stratified sampling. Complete stratified sampling lesson made for my year 10, top set, gcse class. Accordingly, application of stratified sampling method involves dividing population into. What is the best sampling technique to use for determining the average speed of the cars on a section of highway. Continuous data or continuous variables can take any value, e.
This approach is ideal only if the characteristic of interest is distributed homogeneously across the population. A worksheet and exam style practice questions covering gcse stratified sampling. Chapter 5 choosing the type of probability sampling 1 stratified sampling what is stratified sampling. The table shows the number of students who study each of these languages. This means that each sample point represents the attributes of a known number of. We are interested in sampling plans such that results from the sample can be used to make conclusions about the population.
Stratified sampling gcse full lesson teaching resources. Stratified sampling worksheet and exam practice qs. This is a biased sample, because it is unlikely that this sample represents the population of interest. Samples and surveys worksheets with answers cazoom maths. Foot measurement study of the population of taiwan. Jan 27, 2020 in disproportionate stratified random sampling, the different strata do not have the same sampling fractions as each other. In taking a sample of villages from a big state, it is more administratively convenient to consider the districts as strata so that the administrative set up at district level may be used. At a local community college, five math classes are. Stratified random sampling is a type of probability sampling using which researchers can divide the entire population into numerous nonoverlapping, homogeneous strata. A method of probability sampling where all members of the population have an equal chance of being included population is divided into strata sub populations and random samples are drawn from each this increases representativeness as a proportion of each population is. Sampling techniques introduction to sampling distinguishing between a sample and a population simple random sampling step 1. Contacting members of the sample stratified random sampling convenience sampling quota sampling thinking critically about. When a random starting point is chosen, followed by every nth individual, this sampling method is a. More sampling effort is allocated to larger and more variable strata, and less to strata that are more costly to sample.
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