MA241 - Statistics for the Life Science
MA241 Lab 1 - Experimental Design; Probability
Name:
Student Number:
Lab
Fall 2014
1. [2 marks] MA241 has a population of 120 students. The students are listed in alphabetical order, and then divided, in order, into groups of three. The names of each group of three students are written on 40 slips of paper. Then, one slip of paper is chosen in order to get a sample of size n = 3.
Does this represent a simple random sample? Explain why or why not in your own words.
No, this does not represent a simple random sample. The selections of individuals are not independent of each other (for example, Student 1 and Student 2 could both end up in the sample, but Student 1 and Student 4 could not).
2. [2 marks] In sociology research, there is a sampling method called snowball sampling. It is a technique for developing a research sample where existing study subjects recruit future subjects from among their acquaintances. Thus, the group of individuals in the sample appears to grow like a rolling snowball. This sampling technique is often used in hidden populations which are hard for researchers to access (such as drug users).
List two potential problems with this sampling method.
Answers may include:
• It is subject to bias; i.e., people who have many friends are more likely to be recruited into the sample.
• It is inexact, and can produce varied and inaccurate results.
• There is a lack of definite knowledge as to whether or not the sample is an accurate reading of the target population. • This method seems relatively close to voluntary response samples, which have similar problems.
3. [5 marks] Linear regression is a topic that will appear later on in this course. The term “regression” was originally used in 1885 by Sir Francis Galton in his analysis of the relationship between the heights of children and parents. He formulated the “law of universal regression” which specifies that: “each peculiarity in a man is shared by his kinsmen, but on average in a less degree.”
Name:
Student Number:
Lab
Fall 2014
1. [2 marks] MA241 has a population of 120 students. The students are listed in alphabetical order, and then divided, in order, into groups of three. The names of each group of three students are written on 40 slips of paper. Then, one slip of paper is chosen in order to get a sample of size n = 3.
Does this represent a simple random sample? Explain why or why not in your own words.
No, this does not represent a simple random sample. The selections of individuals are not independent of each other (for example, Student 1 and Student 2 could both end up in the sample, but Student 1 and Student 4 could not).
2. [2 marks] In sociology research, there is a sampling method called snowball sampling. It is a technique for developing a research sample where existing study subjects recruit future subjects from among their acquaintances. Thus, the group of individuals in the sample appears to grow like a rolling snowball. This sampling technique is often used in hidden populations which are hard for researchers to access (such as drug users).
List two potential problems with this sampling method.
Answers may include:
• It is subject to bias; i.e., people who have many friends are more likely to be recruited into the sample.
• It is inexact, and can produce varied and inaccurate results.
• There is a lack of definite knowledge as to whether or not the sample is an accurate reading of the target population. • This method seems relatively close to voluntary response samples, which have similar problems.
3. [5 marks] Linear regression is a topic that will appear later on in this course. The term “regression” was originally used in 1885 by Sir Francis Galton in his analysis of the relationship between the heights of children and parents. He formulated the “law of universal regression” which specifies that: “each peculiarity in a man is shared by his kinsmen, but on average in a less degree.”