Stratified sampling questions worksheets and revision mme. In a random sample, every person in the population has the same chance of being selected. Stratified sampling method it is important to note that the strata must be nonoverlapping. May 10, 2014 gcse revision video 31 stratified sampling. Maths revision video and notes on the topic of stratified sampling. The examples are quick and concise with exam style questions, go to gcse maths if you need more indepth explanations. Gcse mathematics stratified sampling questions appear on many exam papers and you can download the questions here. 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. 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.
Jan 06, 2016 stratified sampling deals mainly with fractions and is usually on a gcse calculator question paper. 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. Sampling theory chapter 4 stratified sampling shalabh, iit kanpur page 7 3. In stratified sampling, the population is partitioned into nonoverlapping groups, called strata and a sample is selected by some design within each stratum. 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. A stratified sample will give a sample proportional to the size of the strata. In this method, the elements from each stratum is selected in proportion to the size of the strata. Accordingly, the quota is based on the proportion of subclasses in the population.
A study of stratified sampling in variance reduction. Total sample size k i i nn population n units stratum 1. Stratified random sampling intends to guarantee that the sample represents specific subgroups or strata. Hence, there is a same sampling fraction between the strata. A headteacher wants to find out what year 7 think about their first term at their new school. If the groups are of different sizes, the number of items selected from each group will be proportional. 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. Updated for the 2012 exam ultimate gcse statistics revision guide. 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. Administrative convenience can be exercised in stratified sampling. Sample this is when data is collected from part of the population.
Stratified sampling is a process used in market research that involves dividing the population of interest into smaller groups, called strata. The researcher identifies the different types of people that make up the target population and works out the proportions needed for the sample to be representative. Stratified sampling practice questions corbettmaths. English students, law students, psychology students, engineering students, mathematics students etc. Stratified sampling worksheet and exam practice qs teaching. The population is classified by age as shown in the table below.
Stratified random sampling is a method of sampling that involves the division of a population into smaller groups known as strata. Samples are then pulled from these strata, and analysis is performed to make inferences about the greater population of interest. Study on a stratified sampling investigation method for. Gcse mathematics stratified sampling 3 minute maths. 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. 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.
Divide a habitat into zones which appear different and take samples from each zone. As this method provides greater precision, greater level of accuracy can. Random sampling, stratified sampling, systematic sampling. 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. He decides to ask a stratified sample of 50 students. This completely negates the concept of stratified sampling as a type of probability sampling. Households may be randomly selected from a random sample of streets from a random selection of areas. Stratified sampling is used to select a sample that is representative of different groups. I hope the video helps and please do leave a comment thanks. 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. This is because this type of sampling technique has a high statistical precision compared to simple random sampling.
Select a sample stratified by one category and by more than one category. They can be a little challenging and please do practice all of the problems. A gcse maths worksheet covering stratified sampling. Covers all parts of the gcse syllabus, including sampling methods random and stratified sampling. Chapter 5 choosing the type of probability sampling 1 stratified sampling what is stratified sampling. Stratified random sampling helps minimizing the biasness in selecting the samples. Stratified sampling is when the population can be classified into groups or strata. 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. Stratified random sampling is a method of sampling that involves the division of a population into smaller subgroups known as strata. In order to fully understand stratified sampling, its important to be. For example, geographical regions can be stratified into similar regions by means of some known variable such as habitat type, elevation or soil type. 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. Stratified sampling higher collecting data ccea gcse.
In what follows, the application of stratified sampling in mc yield estimation will be discussed. Stratified random sampling ensures that no any section of the population are underrepresented or overrepresented. Edexcel gcse maths linear 1ma0 stratified sampling answers. Check that you know the total population size this. 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. Jackie is the president of the party planning committee of her school. This is when the population is split into could have sub groups. Stratified sampling gcse full lesson teaching resources.
Gcse maths revision stratified sampling teaching resources. A random sample is taken from particular social categories, e. Lesson includes definition and builds the difficulty of examples which my class found insightful. This was taken from my 150 page workbook which covers many more maths topics. Complete stratified sampling lesson made for my year 10, top set, gcse class. Random sampling of each subpopulation is done, based on its representation within the population as a. Number of sampling units to be drawn from ith stratum.
Sampling theory chapter 4 stratified sampling shalabh, iit kanpur page 2 notations. This lesson can be used for revision for the higher maths gcse. Stratified random sampling is a type of probability sampling technique see our article probability sampling if you do not know what probability sampling is. Want to download the sampling revision notes in pdf format. 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. A typical gcse statistics question on scatter graphs will have the following structure. Gcse revision video 31 stratified sampling youtube. Sampling statistics want to download the sampling revision notes in pdf format. 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. 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. 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. By separating the population into groups age groups, genders, etc.
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. Updated for the 2012 exam ultimate gcse statistics. For example, suppose you want to know about reading habits in the uk. Accordingly, application of stratified sampling method involves dividing population into. Stratified random sampling or stratified sampling, as opposed to simple random sampling, is often used in the field of healthcare management and policy. 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. Stratified sampling dividing sampling into groups, eg three sites from each section of coastline, or five people from each age range. Gcse topic booklet stratified sampling page 1 of 6 1. For example, an urban ward may contain 8 deprived wards and 2 undeprived wards. Stratified random sampling definition investopedia. 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. Gcse statistics revision notes collecting data sample this is.
Suitable for gcse students sitting the 9 1, alevel maths students revision and some key stage 3 students. Previous rounding highest lowest practice questions. A worksheet and exam style practice questions covering gcse stratified sampling. Understanding stratified samples and how to make them. Random and stratified sampling this lesson can be used for revision for the higher maths gcse. Stratified sampling deals mainly with fractions and is usually on a gcse calculator question paper.
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. In stratified random sampling or stratification, the strata. The main things to remember when working with gcse mathematics stratified sampling questions are. In a stratified sample, a proportionate number of measurements are taken is taken from each group. 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. Stratified sample definition and meaning collins english. Other results for edexcel gcse maths linear 1ma0 stratified sampling answers. Suitable for all the big examination boards including aqa, edexcel, ocr and wjec. Random and stratified sampling questions, worksheets, videos.
Use a stratified sampling method to calculate the number of staff from each job type that should be asked to complete the survey. If the groups are of different sizes, the number of items selected from. This text first dissected the relationship between average travel frequency, trip mode structure, and the characteristics of residential areas. Number of sampling units in ith strata 1 k i i nn ni. Simple random sampling is the most recognized probability sampling procedure.
Random and stratified sampling questions, worksheets. Calculate the number of people that should be sampled from each age. 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. Having overlapping subgroups will grant some individuals higher chances of being selected as subject.