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Why are random samples hard to obtain?
Cus
When are two random samples dependent?
Two random samples are dependent if each data value in one sample can be paired with a corresponding data value in the other sample.
Why are random samples more representative of the population than other kinds of samples?
A 'random' sample - covers all age groups, genders, and other criteria. A 'targeted' sample might only cover a small part of the population.
Different types of random and non random sampling?
stratified sampling, in which the population is divided into classes, and random samples are taken from each class;cluster sampling, in which a unit of the sample is a group such as a household; andsystematic sampling, which refers to samples chosen by any system other than random selection.
How many different simple random samples of 7 are possible from a pool of 25?
There are 25C7 different samples of seven from a pool of 25.25C7 = 25!/(7!(25-7)!) = 480 700 different samples of 7
Before George Gallup polling samples were often?
biased.
Before George Gallup which characteristic did polling samples often have?
biased
In a scientific opinion polling a random sample is used to avoid?
bias.
Will all random samples from a given population have the same mean?
Data from random samples will not always include the same values. Values are chosen randomly and they may or may not be the same. So means will vary among random samples.
Why are random samples hard to obtain?
Cus
Scientific polling uses part of the population to measure the whole This sample must be?
random
When are two random samples independent?
z test
When are two random samples dependent?
Two random samples are dependent if each data value in one sample can be paired with a corresponding data value in the other sample.
Why are random samples more representative of the population than other kinds of samples?
A 'random' sample - covers all age groups, genders, and other criteria. A 'targeted' sample might only cover a small part of the population.
What type of sampling produces representative samples?
random sampling
How many simple random samples of size 5 can be selected from a population of size 35?
There are 324,632 possible samples.
Different types of random and non random sampling?
stratified sampling, in which the population is divided into classes, and random samples are taken from each class;cluster sampling, in which a unit of the sample is a group such as a household; andsystematic sampling, which refers to samples chosen by any system other than random selection.
