Chapter 18: Study Design & Data Handling

Question 1

The research question is usually expressed as a(n):

Answer 1

Hypothesis

Question 2

A study attempts to determine if using treats, such as chocolate chips, elicits a desired behavior in rats of moving through a tunnel to a new cage and helps the rats learn the behavior quicker. What is the independent variable?

Answer 2

The treats

Question 3

True or False

In a scientific study, the control group is the group receiving the experimental treatment

Answer 3

False

Question 4

True or False

In any scientific study, the goal is to include as many animals as possible in each group

Answer 4

False

Question 5

True or False

In statistics, the p value is the opposite of the confidence level

Answer 5

True

Question 6

Statistics is a science that deals with the _______, ________, _________, and _________ of data by the use of _________________.

Answer 6

Collection
Classification
Analysis
Interpretation

Probability theory

Question 7

Which criteria should be used in determining the number of animals to be used in a study?
A- the 3Rs principle
B- the confidence level selected
C- the randomization index
D- the normal distribution curve

Answer 7

A- the 3Rs principle

B- the confidence level selected

Question 8

Define dependent variable

Answer 8

The variable that is measured during the study

Question 9

Define independent variable

Answer 9

The variable that is manipulated by the investigator

Question 10

Define control group

Answer 10

A singular group of animals that does not receive the experimental treatment

Question 11

Define treatment group

Answer 11

The animals that receive the experimental treatment

Question 12

Name a statistical method that helps control variables by eliminating personal bias from the study

Answer 12

Randomization

Question 13

If two sets of rat weights are found to be significantly different at a p value of 0.05, which of the following interpretations of the results is the most accurate?
A- there is a 0.05 g difference between the average weight of the rats in group A and group B
B- there is only 5% chance or better that the weights of the rats in the two groups are different
C- there is a at least a 95% probability that the weights of the rats from group A are different from the weight of the rats in group B
D- the mean of the weights of group A rats differ from the mean of the weights of rats in group B by a standard deviation equal to 0.05

Answer 13

C- there is at least a 95% probability that the weights of the rats from group A are different from the weight of the rats in group B

Question 14

True or False

For a sample that has a normal distribution, 95% of the data points will fall within +/- 2 SD

Answer 14

True

Question 15

What is the difference between the confidence level and the p value?

Answer 15

The index of certainty that the difference is due to the experimental treatment

Question 16

What factor is controlled by randomization?

Answer 16

Bias

Question 17

Explain the difference between an experimental and a null hypothesis

Answer 17

The experimental hypothesis is a prediction of the results of a study; it is a statement of the answer the investigator expects to find to the research question. The null hypothesis states that there is no difference between the means of the two groups; that is, the treatment has no effect on the dependent variable

Question 18

In a normal distribution, what percentage of measurements fall between the mean and plus or minus 1 standard deviation

Answer 18

68%

Question 19

In a normal distribution, what percentage of measurements fall between the mean and plus or minus 2 standard deviations

Answer 19

95%

Question 20

In a normal distribution, what percentage of measurements fall between the mean and plus or minus 3 standard deviations

Answer 20

99%

Question 21

What is the definition of standard deviation

Answer 21

Measure of the dispersion of data

Question 22

What is the definition of null hypothesis

Answer 22

A statement that there is no difference between the means of the two groups

Question 23

What is the definition of variable

Answer 23

Anything that can potentially affect the results of the study

Question 24

What is the definition of p value

Answer 24

The probability that the observed difference happened by chance alone

Question 25

What is the definition of confidence value

Answer 25

Index of certainty

Question 26

What is the definition of sample size

Answer 26

The number of experimental units in a group

Question 27

Information based on reported examples is known as:
A- Erroneous
B- Practical
C- Anecdotal
D- Biased

Answer 27

C- Anecdotal

Question 28

Which statement regarding standard deviations is FALSE?
A- How far data range above or below the mean is stated as a number of standard deviations
B- The standard deviations, means, and sizes of two groups are used to test for a significant difference between the groups
C- In any distribution, the same percentage of data points will fall within one standard deviation from the mean.
D- A standard deviation may be a positive or a negative value

Answer 28

C- In any distribution, the same percentage of data points will fall within one standard deviation from the mean

Question 29

Details of the assessed treatment(s) and measurements are describes by the:
A- Experimental hypothesis
B- Research question
C- Study design
D- Statistical analysis

Answer 29

C- Study design

Question 30

If results from a study can be replicated in some animal studies but no t in others, the study lacks:
A- Power
B- Generality
C- Objectivity
D- Accuracy

Answer 30

B- Generality

Question 31

What best defines the term “variable” as used in the biomedical research field?
A- It refers to something that cannot be measured accurately
B- It represents anything that can affect the results of a study
C- It represents anything that is not controlled during the study
D- It refers to what is being measured during the study

Answer 31

B- It represents anything that can affect the results of a study

Question 32

Which is NOT a common originating source for a research question?
A- Results from a study
B- A literature review
C- An investigator’s observation
D- A science textbook

Answer 32

D- A science textbook

Question 33

A group of investigators think that cages housing mice on paper bedding will have higher ammonia levels than those on hard wood, but they conduct a study and conclude that any difference between groups is due to chance and not to any effect created by the different bedding types.  Their conclusion supports which of the following?
A- Experimental hypothesis
B- Null hypothesis
C- Alternative hypothesis
D- Stated objectives

Answer 33

B- Null hypothesis

Question 34

A(n) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is an assumption evaluated by research.
A- Hypothesis
B- Objective
C- Observation 
D- Theory

Answer 34

A- Hypothesis

Question 35

Which action will NOT be taken at the end of our study if the p-value of statistical test is less than 0.05?
A- Reject the null hypothesis
B- Conclude that the alternative hypothesis is true
C- Accept that there is a 5% probability that the difference is due to chance
D- Conclude that there is no significant difference between groups

Answer 35

D- Conclude that there is no significant difference between groups

Question 36

If an article states that the results show a significant difference at the 0.05 level, what does this mean?
A- There is a 5% probability that the difference is real
B- The probability of finding a difference is 5%
C- There is a 95% probability that the difference is real
D- There were not enough animals in the experimental group to reach a conclusion

Answer 36

C- There is a 95% probability that the difference is real

Question 37

If a treatment would actually be effective, but a significant effect was not detected in the study (the null hypothesis was accepted), the study lacked:
A- Bias
B- Variability
C- Generality
D- Power

Answer 37

D- Power

Question 38

The confidence level is an index of:
A- Certainty
B- Accuracy
C- p-value
D- Average value

Answer 38

A- Certainty

Question 39

A(n) \_\_\_\_\_\_\_ is an assumption evaluated by research.
A- Hypothesis
B- Observation
C- Theory
D- Objective

Answer 39

A- Hypothesis

Question 40

In a study testing the effects of different types of analgesia on wound healing: 1) some mice are housed closer to a refrigerator that is known to cause cages on a rack to vibrate; 2) one treatment group is composed only of female mice who weigh less than males; and 3) one investigator coding the severity of wounds over times believes that only one of the analgesia types is effective.  If a significant effect is found when the data is analyzed, it could be the result of a(n):
A- Independent variable
B- Sex and weight
C- Bias
D- Nonexperimental variable

Answer 40

D- Nonexperimental variable

Question 41

Which phrase best defines “bias” in research?
A- Influence on study data by investigators or conditions
B- Effect of study inclusion on control group
C- The strength of the treatment at the lowest level tested
D- The influence of chance upon study results

Answer 41

A- Influence on study data by investigators or conditions

Question 42

If two sets of rat weight data are found to be significantly different at a p-value of 0.01, whih of the following interpretations of the results is the most accurate?
A- The mean of the weights of group A differs from the mean of the weights of rats in group B by a standard deviation equal to 0.01
B- There is only a 1% chance or better that the weights of the rats in the two groups are different
C- There is a 0.01 g difference between the average weight of the rats in group A and group B
D- There is at least a 99% probability that the weights of the rats from group A are different from the weights of the rats in group B due to the treatment

Answer 42

D- There is at least a 99% probability that the weights of the rats from group A are different from the weights of the rats in group B due to the treatment