By: Jalen Rebolledo and Manilou Allanic
Factors affecting sample selection.
sampling methods and its advantages and disadvantages
Steps on random sampling
By: Jalen Rebolledo and Manilou Allanic
Factors affecting sample selection.
sampling methods and its advantages and disadvantages
Steps on random sampling
Sampling is concerned with the selection of a subset of individuals from within a statistical population to estimate characteristics of the whole population
Stratified Sampling and Cluster Sampling that are most commonly contrasted by the people. There is a big difference between stratified and cluster sampling, which in the first sampling technique, the sample is created out of the random selection of elements from all the strata while in the second method, all the units of the randomly selected clusters form a sample. Just have a look for better understanding.
Systematic sampling in probability sampling Sachin H
This is a systematic sample in probability sampling which is consider to be one of the technics of sampling . It is most useful in certain circumstances in Random sampling.
Sampling is concerned with the selection of a subset of individuals from within a statistical population to estimate characteristics of the whole population
Stratified Sampling and Cluster Sampling that are most commonly contrasted by the people. There is a big difference between stratified and cluster sampling, which in the first sampling technique, the sample is created out of the random selection of elements from all the strata while in the second method, all the units of the randomly selected clusters form a sample. Just have a look for better understanding.
Systematic sampling in probability sampling Sachin H
This is a systematic sample in probability sampling which is consider to be one of the technics of sampling . It is most useful in certain circumstances in Random sampling.
Qualitative sampling design is a key step in qualitative research, especially for rural development, researchers
this document provides the necessary details on the procedures to follow
Sampling is procedure or process of selecting some units from the population with some common characteristics and is primarily concerned with the collection of data of some selected units of the population.
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Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
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June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
2. Learning Objectives
• To become familiar with sample design terminology
• To understand the differences between probability and non probability
sampling methods
• To learn how to take four types of probability samples: simple random
samples, systematic samples, cluster samples, and stratified samples
• To learn how to take four types of non probability samples: convenience
samples, purposive samples, referral samples, and quota samples
• To acquire the skills to administer different types of samples, including online
samples
• To be able to develop a sample plan
6. Census
• A census is an accounting of
the complete population.
• The U.S. census is taken every
10 years by the U.S. Census
Bureau (www.census.gov).
7. Basic Concepts in
Sampling
• Sample: a subset of the
population that should
represent the entire group
• Sample unit: the basic level of
investigation
8. Basic Concepts in Sampling
• A sample frame: a master list of the entire population
• Sampling frame error: the degree to which the sample frame fails to
account for all of the population
10. Probability samples: ones in which members of the
population have a known chance (probability) of
• Probability samples: ones in which members of the population have a
known chance (probability) of being selected into the sample
• Non probability samples: instances in which the chances (probability) of
selecting members from the population into the sample are unknown
12. Probability Sampling:
• Simple random sampling: the probability of being selected into the sample
is “known” and equal for all members of the population.
• The random device method involves using an apparatus of some sort to
ensure that every member of the population has the same chance of being
selected into the sample.
• The random numbers method involves small populations that are easily
accommodated by the physical aspects of the device.
13. Probability Sampling:
• Simple Random Sampling Equation:
• Probability of Selection = Sample Size/Population Size
• Example #1: Population = 250,000, Sample = 10,000
• Example #3: Population = 1,000,000, Sample = 40,000
• Which group has a higher probability of being selected?
14. Probability Sampling:
• Simple Random Sampling Equation:
• Probability of Selection = Sample Size/Population Size
• Example #1: Population = 250,000, Sample = 10,000
• Probability of Selection = 1,000/250,000 = 4% (Chance of being
selected)
• Example #3: Population = 1,000,000, Sample = 40,000
• Probability of Selection = 40,000/1,000,000 = 4%
15. Probability Sampling
• Systematic sampling: way to select a random sample from a directory or list
that is much more efficient than simple random sampling
• To develop the sample, the Skip Interval is used
• Skip Interval = Population List Size/Sample Size
16. Probability Sampling
• Skip Interval = Population List Size/Sample Size
• Population List Size = 2,000
• Sample Size = 200
• Skip Interval = 2,000/200 = 10
• What does this mean? Every 10th person on the list is chosen for the
sample
17. Probability Sampling
• Cluster sampling: method in
which the population is divided
into subgroups, called
“clusters,” each of which could
represent the entire population
• Area sampling is a form of
cluster sampling; the
geographic area is divided into
clusters.
• Disadvantage: the cluster
specification error occurs when
the clusters are not
homogeneous.
18. Area (Cluster)
Sampling
• One-step area sample: the
researcher may believe the
various geographic areas
(clusters) to be sufficiently
identical to allow concentrating
his or her attention on just one
area and then generalizing the
results to the full population.
• Two-step area sample: the
researcher selects a random
sample of areas, and then he or
she decides on a probability
method to sample individuals
within the chosen areas.
19. Probability Sampling
• Stratified sampling: separates
the population into different
subgroups and then samples all
of these subgroups
FIGURE 9.2
Stratified Simple
Random Sampling
21. Non probability Sampling
• With non probability sampling methods selection is not based on fairness,
equity, or equal chance.
• Convenience sampling
• Purposive sampling
• Referral sampling
• Quota sampling
22. Non probability Sampling
• Convenience samples: samples drawn at the convenience of the interviewer
• Purposive samples: requires a judgment or an “educated guess” as to who
should represent the population
• Referral samples: require respondents to provide the names of prospective
respondents
• Quota samples: specified percentages of the total sample for various types
of individuals to be interviewed
23. Convenience Sample Location
Convenience Sample
Location
What students would
be overrepresented?
What Students would
be underrepresented
University Rec Center
University Commons
Library
Physics 401 (Advanced
STEM Class)
24. Online Sampling Techniques
• Online panels: large numbers of individuals who have agreed to participate in
online surveys
• River samples: created via the use of banners, pop-ups, or other online
devices that invite website visitors to take part in the survey
• E-mail list samples: purchased or otherwise procured from someone or
some company that has compiled email addresses of opt-in members of the
population of interest
25. Why Samples?
• A census is not usually possible
• Think how hard it would be to interview every Point Park Students
• If done correctly (Chapter 10) - the sample using probability sample methods
can be very represented of the overall population