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. In order to fully understand stratified sampling, its important to be. A random sample may by chance miss all the undeprived areas. Covers all parts of the gcse syllabus, including sampling methods random and stratified sampling. Understanding stratified samples and how to make them. The results showed that conducting a stratified resident travel investigation in accordance with the characteristics of residential areas will yield samples with much smaller differences and reduce the investigation sampling rate. Number of sampling units to be drawn from ith stratum.
Other results for edexcel gcse maths linear 1ma0 stratified sampling answers. Use a stratified sampling method to calculate the number of staff from each job type that should be asked to complete the survey. Calculate the number of people that should be sampled from each age. Maths revision video and notes on the topic of stratified sampling.
He wants to find out how often people have been to the library in the last year. Unlike the simple random sample and the systematic random sample, sometimes we are interested in particular strata meaning groups within the population e. In stratified random sampling or stratification, the strata. This was taken from my 150 page workbook which covers many more maths topics. A typical gcse statistics question on scatter graphs will have the following structure. In stratified sampling, we divide the population into nonoverlapping subgroups called strata and then use simple random sampling method to select a proportionate number of individuals from each strata. This is when the population is split into could have sub groups. In what follows, the application of stratified sampling in mc yield estimation will be discussed. Sampling is the process of looking at a small selection of peopleobjects from a wider population in order to learn new information about that population.
Gcse topic booklet stratified sampling page 1 of 6 1. Accordingly, the quota is based on the proportion of subclasses in the population. Sep 30, 20 stratified random sampling or stratified sampling, as opposed to simple random sampling, is often used in the field of healthcare management and policy. English students, law students, psychology students, engineering students, mathematics students etc. A stratified sample is defined as one resulting from classification of population into mutually exclusive groups, called strata, and choosing a simple random sample from each stratum. A headteacher wants to find out what year 7 think about their first term at their new school. Apr, 2019 stratified random sampling provides the benefit of a more accurate sampling of a population, but can be disadvantageous when researchers cant classify every member of the population into a subgroup. Divide a habitat into zones which appear different and take samples from each zone. Use a stratified sampling method to calculate how many people from each country should invited to the conference an international festival is to held, but tickets are limited to 50. The examples are quick and concise with exam style questions, go to gcse maths if you need more indepth explanations. Stratified sampling practice questions corbettmaths. Stratified sample a sample including each sub category of the target population so for example, if your target population is birmingham university students, each sub category would include each university degree. Quota sampling is a nonprobability sampling technique in which researchers look for specific qualities or traits in their respondents, and then take a sample that is in proportion to a population of interest. Random and stratified sampling questions, worksheets.
Stratified random sampling intends to guarantee that the sample represents specific subgroups or strata. Edexcel gcse 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. For example, suppose you want to know about reading habits in the uk. Stratified sampling an important objective in any estimation problem is to obtain an estimator of a population parameter which can take care of the salient features of the population. Random and stratified sampling this lesson can be used for revision for the higher maths gcse. Jackie is the president of the party planning committee of her school. The population is classified by age as shown in the table below. This completely negates the concept of stratified sampling as a type of probability sampling. Proportionate allocation uses a sampling fraction in each of the strata that is proportional to that of the total population. A study of stratified sampling in variance reduction.
Random sampling, stratified sampling, systematic sampling. Proportional stratified sampling pdf stratified sampling offers significant improvement to simple random. Edexcel gcse maths linear 1ma0 stratified sampling answers. This is because this type of sampling technique has a high statistical precision compared to simple random sampling. Stratified random sampling or stratified sampling, as opposed to simple random sampling, is often used in the field of healthcare management and policy. A stratified sample will give a sample proportional to the size of the strata. 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. If the groups are of different sizes, the number of items selected from each group will be proportional. 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. Select a sample stratified by one category and by more than one category.
Stratified random sampling definition investopedia. Stratified sampling deals mainly with fractions and is usually on a gcse calculator question paper. Sampling theory chapter 4 stratified sampling shalabh, iit kanpur page 7 3. Stratified random sampling is a method of sampling that involves the division of a population into smaller subgroups known as strata. For example, if a class has 20 students, 18 male and 2 female, and a researcher wanted a sample of 10, the sample would consist of 9 randomly chosen males and 1 randomly chosen. Number of sampling units in ith strata 1 k i i nn ni. Having overlapping subgroups will grant some individuals higher chances of being selected as subject. Accordingly, application of stratified sampling method involves dividing population into. Gcse maths revision stratified sampling teaching resources. It is possible to combine stratified sampling with random. I hope the video helps and please do leave a comment thanks. Random sampling of each subpopulation is done, based on its representation within the population as a. May 10, 2014 gcse revision video 31 stratified sampling.
Stratified sampling is when the population can be classified into groups or strata. Stratified sample definition and meaning collins english. Stratified sampling is a method we can use to make our sample more representative. Jan 06, 2016 stratified sampling deals mainly with fractions and is usually on a gcse calculator question paper. Simple random sampling is the most recognized probability sampling procedure. Hence, there is a same sampling fraction between the strata.
In a random sample, every person in the population has the same chance of being selected. Stratified random sampling helps minimizing the biasness in selecting the samples. Households may be randomly selected from a random sample of streets from a random selection of areas. Stratified random sampling is a method of sampling that involves the division of a population into smaller groups known as strata. Chapter 5 choosing the type of probability sampling 1 stratified sampling what is stratified sampling. Gcse mathematics stratified sampling 3 minute maths. 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. Want to download the sampling revision notes in pdf format. Stratified sampling questions worksheets and revision mme. Sampling statistics want to download the sampling revision notes in pdf format.
Suitable for gcse students sitting the 9 1, alevel maths students revision and some key stage 3 students. Three techniques are typically used in carrying out step 6. 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. Gcse mathematics stratified sampling questions appear on many exam papers and you can download the questions here. Stratified sampling worksheet and exam practice qs teaching. A worksheet and exam style practice questions covering gcse stratified sampling. The main things to remember when working with gcse mathematics stratified sampling questions are. This text first dissected the relationship between average travel frequency, trip mode structure, and the characteristics of residential areas. Stratified sampling dividing sampling into groups, eg three sites from each section of coastline, or five people from each age range. Gcse statistics revision notes collecting data sample this is. Sampling theory chapter 4 stratified sampling shalabh, iit kanpur page 2 notations.
Stratified sampling is a process used in market research that involves dividing the population of interest into smaller groups, called strata. In a stratified sample, a proportionate number of measurements are taken is taken from each group. Random and stratified sampling questions, worksheets, videos. Stratified sampling gcse full lesson teaching resources.
Administrative convenience can be exercised in stratified sampling. Check that you know the total population size this. Gcse revision video 31 stratified sampling youtube. Suitable for all the big examination boards including aqa, edexcel, ocr and wjec. He decides to ask a stratified sample of 50 students. A gcse maths worksheet covering stratified sampling. Study on a stratified sampling investigation method for. Stratified random sampling is a type of probability sampling technique see our article probability sampling if you do not know what probability sampling is. The main difference between quota and stratified sampling can be explained in a way that in quota sampling researchers use nonrandom sampling methods to gather data from one stratum until the required quota fixed by the researcher is fulfilled. Stratified sampling method it is important to note that the strata must be nonoverlapping. To do this, you might ask 500 people from the uk how many books they finished last year this is a sample. In stratified sampling, the population is partitioned into nonoverlapping groups, called strata and a sample is selected by some design within each stratum.
Stratified sampling is used to select a sample that is representative of different groups. 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. For example, an urban ward may contain 8 deprived wards and 2 undeprived wards. Right now, the party planning committee is planning a winter formal.
Stratified sampling higher collecting data ccea gcse. Lesson includes definition and builds the difficulty of examples which my class found insightful. Stratified sampling offers significant improvement to simple random sampling. For example, if vegetation cover in an area of heathland is 60% heather and 40% gorse, for a stratified sample take 60% of the samples from within heather and 40% of the samples from within gorse. Complete stratified sampling lesson made for my year 10, top set, gcse class. Sample this is when data is collected from part of the population. For example, geographical regions can be stratified into similar regions by means of some known variable such as habitat type, elevation or soil type.
A random sample is taken from particular social categories, e. In this method, the elements from each stratum is selected in proportion to the size of the strata. This lesson can be used for revision for the higher maths gcse. Total sample size k i i nn population n units stratum 1. 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. Updated for the 2012 exam ultimate gcse statistics revision guide.
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