Introduction to a range of geography fieldwork sampling techniques and strategies, including minimum sample size, urban sampling, random and systematic sampling, stratified sampling and optimum quadrat size calculation. If you haven't already done it, work through the unit on sampling data in fieldwork on the powerpoint. Number of sampling units to be drawn from ith stratum.
PPT Formalizing the Concepts STRATIFICATION PowerPoint
0000018598 00000 n in this type of sampling, we divide the populations into certain classes or categories on the basis of their characteristics / features such as gender, age etc.
The strata is formed based on some common characteristics in the population data.
In a stratified sample, a proportionate number of measurements are taken is taken from each group. For example, an urban ward may contain 8 deprived wards and 2 undeprived wards. No population element can be excluded. Total sample size k i i nn population (n units) stratum 1
We would therefore make sure that our sample included a representative proportion of the elderly and very young.
A random sample may by chance miss all the undeprived areas. Revised on october 5, 2021. Stratified sampling is used where there are small areas within a larger study location which are clearly different. It is possible to combine stratified sampling with random.
Stratified sampling is helpful when a geographical area contains a wide variety of unique populations.
In a stratified sample, researchers divide a population into homogeneous subpopulations called strata (the plural of stratum) based on specific characteristics (e.g., race, gender identity, location, etc.). Or look at it again to help fill in any gaps in what you know! Stratified sampling if it’s known that there are different groups or classes in a population, such as different rock types in an area, or different ethnic groups in a city, it is possible to make sure a representative sample is included in a. This is when the population is split into could have sub groups.
Data presentation techniques, fieldwork methodology, mapping techniques and statistical methods are also included.
Stratified sampling is a method of obtaining a representative sample from a population that researchers have divided into relatively similar subpopulations (strata). Number of strata ni : Stratified sampling is a type of sampling method in which the total population is divided into smaller groups or strata to complete the sampling process. There is not enough time, energy, money, labour/man power, equipment etc to measure every single item or site within the sampling area.
Stratified sampling provides an equal representation of an area by providing a sample size in proportion to the overall population.
For example, an urban ward may contain 8 deprived super output areas and 2 undeprived super output areas. The strata should also be collectively exhaustive: Learn more about the definition, characteristics, and examples of stratified random sampling, and understand when. We use the following symbols and notations:
Each subgroup or stratum consists of items that have common characteristics.
Every element in the population must be assigned to only one stratum. Stratification is the process of dividing members of the population into homogeneous subgroups before sampling. Stratified sampling is a random sampling method of dividing the population into various subgroups or strata and drawing a random sample from each. Number of sampling units in ith strata 1 k i i nn ni:
For example imagine i want to to survey 5 streets in an area which has 10 streets in it.
This sampling method is widely used in human research or political surveys. Published on september 18, 2020 by lauren thomas. Stratified sampling this is where a proportionate number of observations is taken from each part of the population. Sampling theory| chapter 4 | stratified sampling | shalabh, iit kanpur page 2 notations:
For example, let's say you're trying to do a.
A stratified random sampling involves dividing the entire population into homogeneous groups called strata (plural for stratum). Formed, deposited, or arranged in stable layers or strata such forced ascent of stable air leads to the formation of a stratified cloud layer that is large horizontally. The strata should be mutually exclusive:
