Stratified sampling module 3 session 6 session objectives to introduce basic sampling concepts in stratified sampling demonstrate how to select a random sample using. With this quiz and worksheet, youll be asked to differentiate cluster. 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. Sampling techniques gcse statistics teaching resources. It is applicable to both qualitative and quantitative methods. Then convenience or judgment sampling is used to select the. Randomly select 63 women and 37 men to take the survey stratified random sampling 633 women x 110. The population is classified by age as shown in the table below. Stratified sampling is a method we can use to make our sample more representative. In geography fieldwork, times of day, week and year, the choice of locations to collect data, and the weather can all lead to bias. Timss 2007 used a twostage stratified cluster sampling design. Sampling and sampling distributions aims of sampling probability distributions sampling distributions the central limit theorem types of samples 47 disproportionate stratified sample stratified random sampling stratified random sample a method of sampling obtained by 1 dividing the population into subgroups based on one or more variables central to our analysis and 2 then drawing a.
This is when the population is split into could have sub groups. Textbook example survey factory employees about new safety initiatives. Sampling 2 stratified random powerpoint maths or math. Stratification is the process of dividing members of the population into homogeneous subgroups before sampling. Definition of stratified sampling a stratified sample is a probability sampling technique in which the researcher divides the entire target population into different subgroups, or strata, and then randomly selects the final subjects proportionally from the different strata. Sometimes it is possible to increase the accuracy by separating samples from different parts of a population. Sampling method strengths weaknesses stratified sampling this involves picking people from different groups within the population eg. All students should be able to identify a union and intersect using set notation. Stratified sampling is a method of sampling from a population. Stratified sampling gcse mathematics lesson and worksheet. Take observations at individual points, like separate houses on a street. We can also get more precise estimation by changing the sampling scheme.
Ppt gcse statistics revision powerpoint presentation free. For example, an urban ward may contain 8 deprived wards and 2 undeprived wards. If you are following the edexcel new maths gcse, then you may well have noticed the introduction of a delightful addition to the wonderful world of sampling the capturerecapture method. Stratified sampling is a sampling technique where the researcher divides or stratifies the target group into sections, each representing a key group or characteristic that should be present in the final sample. Choose a random sample from each of the subgroups that were stratified. Choosing your friends may lead to the wrong conclusion. In a stratified sample, a proportionate number of measurements are taken is taken from each group. There are three methods of sampling to help overcome bias. Something that until now had been confined to biology classrooms has now happily found its way onto the maths syllabus. This is because this type of sampling technique has a high statistical precision compared to simple random sampling. Make your own animated videos and animated presentations for free. Understanding stratified samples and how to make them. Sampling helps estimate the characteristics of a large population through the use of a smaller representative group.
Stratified sampling questions worksheets and revision mme. Different sampling methods and how to calculate stratified sample size using equal proportions. Sampling sampling is the process of collecting data from some sites or people in order to obtain a perspective on the population. This type of sampling is used when the research is focused on participants with very specific characteristics such as being members of a gang. Students should carryout the methods of sampling as you go through the powerpoint. Here only the first sampling unit is selected at random and the remaining units are automatically selected in a definite sequence at equal intervals.
Stratified sample by brianna mccreadybranch on prezi. Systematic sampling has slightly variation from simple random sampling. We look at the idea that stratified random sampling can be used where the population under consideration separates naturally into subgroups or strata and that numbers taken in each of these samples is proportional to the size of the group. Scribd is the worlds largest social reading and publishing site. Sampling statistics want to download the sampling revision notes in pdf format. I am struggling to create a stratified sample of size 100 using stratified random sampling with 3078 observations. The design effect of twostage stratified cluster sampling. As learning progresses students are challenged to work the problem in reverse by finding the population of each strata given the sampling size. Aug 24, 2012 this video explains stratified sampling.
When a population is divided up into groups, taking a stratified sample ensures that each group is asked in the correct proportion. I used it for a 30 minute lesson, so it will need adapting for a full lesson depending on class ability. Stratified sampling simple random sampling means that each record in the population has the same chance of being selected. A random sample may by chance miss all the undeprived areas. Download ppt gcse data handling coursework 1 stratified sampling simple random sampling means that each record in the population has the same chance. Jan 27, 2020 a stratified sample can also be smaller in size than simple random samples, which can save a lot of time, money, and effort for the researchers. Introduction to sampling techniques including worksheets on random sampling and. If the groups are of different sizes, the number of items selected from.
Sampling ppt stratified sampling sampling statistics. Stratified sampling stratified sampling is when the population can be classified into groups or. Random and stratified sampling this lesson can be used for revision for the higher maths gcse. As learning progresses students are challenged to use the union and intersection to calculate a probability. This is a tutor2u classic and a really fun lesson that requires minimal teacher input. Stratified sampling is the process of selecting units deliberately from various locations within a lot or batch or from various phases or periods of a process to obtain a sample. Covers all parts of the gcse syllabus, including sampling methods random and stratified sampling. Take observations along a line, like up a beach from sea shore to base of the cliffs.
Stratified random sampling intends to guarantee that the sample. For the full list of videos and more revision resources visit uk. Ppt stratified sampling powerpoint presentation free to. Handling data and statistics powerpoint maths or math. Download powerpoint download notebook download flipchart download worksheet download. The sample will be representative and give the point of view of all the different groups in the population. Sampling methods ppt stratified sampling randomness. This can be useful in market research, medical testing, and product development. Stratified sampling divide sampling frame into homogeneous subgroups strata e. What is the difference between systematic sampling and. Inverse transform method u y m x x sampling random number generator model gy 3 importance sampling. Stratified random sampling definition investopedia. Gcse 1 9 maths lesson includes a gcse maths revision worksheet, lesson plan, powerpoint, notebook and flipchart.
Divide the population into the subgroups so that the subgroup will be homogeneous. In a biased sample, some elements of the population are less likely to be included than others. For example, in the case above of a shading point tracing five rays on the first bounce, each of which traces three on the second bounce, we would like to have each group of three be stratified but in a such a way that all fifteen rays are also well stratified. Feb 15, 2009 stratified random sampling slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Download powerpoint download notebook download flipchart download worksheet scheme of work link. Random and stratified sampling questions, worksheets. The school is the cluster with the children being selected randomly from within the cluster. Stratified random sampling is a method of sampling that involves the division of a population into smaller subgroups known as strata.
The second powerpoint is a random name selector which i used for random sampling. However, it is important that a sample is representative of the population. The examples are quick and concise with exam style questions, go to gcse maths if you need more indepth explanations. Each type of vehicle is to be represented in the sample. Cluster random sampling is one of many methods used to gain information about a population. Want to download the sampling revision notes in pdf format. Data handling and statistics powerpoint maths presentations. These will be internally stratified but the set at each shading point will be independent of the sets at the other shading points. Stratified sampling is when the population can be classified into groups or strata. Mar 14, 2017 if you are following the edexcel new maths gcse, then you may well have noticed the introduction of a delightful addition to the wonderful world of sampling the capturerecapture method.
Stratified sampling a random sample from a homogeneous subgroup a. Stratified sampling worksheet worksheet teacher made twinkl. Sign up now to download sampling sampling twinkl ks3 ks4 maths ks4gcse maths foundation. Calculate the number of people that should be sampled from each age. Stratified sampling gcse full lesson teaching resources.
Complete stratified sampling lesson made for my year 10, top set, gcse class. Sample b supports the idea of random sampling so everyone has a chance to be included. Systematic sampling select sample at regular intervals based on sampling fraction cluster sampling sample units not identified independently but in a group or cluster provides logistical advantage. We are working hard on a new platform for setting, building and monitoring homework. If you continue browsing the site, you agree to the use of cookies on this website. Feb 02, 2015 presentation on stratified sampling 1. Gcse statistics revision is the property of its rightful owner. Stratified sampling is a probability sampling technique wherein the researcher divides the entire population into different subgroups or strata, then randomly selects the final subjects proportionally from the differentstrata. The inspector decides to sample 10% of the vehicles. This lesson can be used for revision for the higher maths gcse. Sampling over space three strategies for area sampling.
Students learn how to calculate the union and intersection of sets using venn diagrams. Stratified sampling is used to select a sample that is representative of different groups. When nsamples is one, the sample returned in the ray will be stratified across each related set of shading points as determined by the ray tree inheritance. Farms92 600 as strata, and by using proportional allocation.
Similar to stratified sampling but the groups are selected for their geographical location. Like stratified sampling, the researcher first identifies the stratums and their proportions as they are represented in the population. To download this file, click the button below to signup it only takes a minute and youll be brought right back to this page to start the download. This sample will not represent the correct number of children in your classmates families. In the future, we would like to allow cooperative stratification. Gcse data handling coursework 1 stratified sampling simple. Disadvantages advantages stratified sampling requires more administrative effort than simple random sampling considering the additional division of samples based on characteristics can provide greater accuracy smaller and more accurate samples can be used this is used when. By separating the population into groups age groups, genders, etc.
Covers all aspects of the gcse syllabus, including limitations of sampling, random sampling and capture, tag and release questions. In the first stage, about 150 schools were selected according to some variables of interest, such as school types or locations. A teacher wants a sample of 50 people from a school. You can view a full sample of this activity above and download the complete. In stratified random sampling or stratification, the strata. Proportionate allocation uses a sampling fraction in each of the strata that is proportional to that of the total population. Having identified and contacted one gang member the researcher asks to be put in touch with any friends or associates who are also gang members.
Stratified sampling is a probability sampling technique wherein the researcher divides the entire population into different subgroups or strata, then randomly selects the final subjects proportionally from the different strata. In the second stage, which is the clustering sampling stage, one or. 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. Quota sampling is the nonprobability equivalent of stratified sampling. Systematic sampling and stratified sampling are the types of probability sampling design. The conditions the stratified random sampling have to meet are. Students learn the difference between different types of sampling methods and how to calculate a stratified sample size using equal proportions. To see all of the work i do for tes maths, including resource of the week, inspect the spec, maths newsletters and topic collections, please visit the tes maths blog here what is it.
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