How does cost play a factor in whether researchers use a sample or the total population? There are several types of random sampling. What are the different types of random sampling? When is it best to use what kind of study or population? How does the researcher decide which type of randomization to use? One example is a convenience sample. When do you think researchers use this? The most "famous" convenience sample is psych 100 college students, especially on large campuses. Why would they be a convenience sample? What population could you generalize to if you use a class of psych 100 students as your sample? Could they extend beyond their own "group"? What considerations would you have to make if you used this kind of class for your sample and wanted to then generalize to everyone else?

What is the goal of using the sample? What are researchers trying to do?

Solution Preview

Hi,
Cost is one of the most important factors when dealing with sample vs population.

For every person you include in your research, you must think of the costs:
- cost of recruiting the person to participate
- time to administer the questionnaire if done face-to-face; cost of hosting the server if done on-line
- if your give an indemnity to the person for their participation
- data entry of their results
- analysis of their data

So this could really add up. Therefore you need to think of your budget - if you budget is a certain value you might not have enough resources to poll every single person in your population. The cost-effective way would be to take a random sample that is large enough to represent the population, and work with these individuals.

Different types of random sample:

simple: here you have a pool of people, and you just randomly select people from the pool to be in your sample
Stratified sampling: if you have sub-samples within the population, you would make sure to select individuals from each ...

Solution Summary

This posting explains how cost can influence your decision wether to use a sample or the entire population. It gives a cost-effective solution in making sure that your research is sound when dealing with samples.

Can you tell me why are samples studied when we want to know aboutpopulations? Why are random samples used instead of just any sample? How would you determine an appropriate sample size? If there are any reference please provide.

Please help with the following problems involving normal distribution andpopulations.
Based off the three requirements that must be met before an analysis of variance test (ANOVA) can be used:
1. Samples must be randomly selected from the populations to be evaluated.
2. Allpopulations from which the samples are selected

Greek letters are used to describe characteristics of
A) samplesandpopulations.
B) samplesand sampling distributions.
C) sampling distributions andpopulations.
D) samples, sampling distributions, andpopulations.

If we are testing for the difference between the means of 2 related populations with samples of n1 = 20 and n2 = 20, the number of degrees of freedom is equal to
39
19
18
Show all work.

SS within samples is a sum of squares representing the variation that is assumed to be common to all the populations being considered. Is this true? Explain

The following ANOVA table based on information obtained for 3 samples from 3 independent populations that are normally distributed with equal variances has a few missing values.
a) Find the missing values and complete the ANOVA table.
b) Using α = .01, what is your conclusion for the test with the null hypothesis that

Consider the following hypothesis test. See attached file for full problem description.
Consider the following hypothesis test
The following data are from matched samples taken form two populations.
Populations
Element 1 2
1 21 20
2 28 26
3 18 18
4 20 20
5 26 24

Which of the following assumptions is not made for the F test for comparing three or more means?
A) The populations from which the samples were obtained must be normally distributed
B) The samples must be independent of each other
C) The sample sizes must be equal.
D) The variances of the populations must be equal

What is a test of a proportion and give an example.
What test do you use when one sample is smalland the other large?
Explain the difference between testing one sample with a parameter and testing two samples.
What are the likes and differences between the ttable and the z table?
When would you use a two pop

I have completed the problem. But I am knowing how to check the normality assumptions of both population. I used minitab for output.
Lesson 10, Practice Problems
1. Problem 6.8: First check assumptions by verification that there are both (1) independent samples from the two populationsand (2) that data in each sample are