Chapter 18: Study Design & Data Handling Flashcards
The research question is usually expressed as a(n):
Hypothesis
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?
The treats
True or False
In a scientific study, the control group is the group receiving the experimental treatment
False
True or False
In any scientific study, the goal is to include as many animals as possible in each group
False
True or False
In statistics, the p value is the opposite of the confidence level
True
Statistics is a science that deals with the _______, ________, _________, and _________ of data by the use of _________________.
Collection
Classification
Analysis
Interpretation
Probability theory
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
A- the 3Rs principle
B- the confidence level selected
Define dependent variable
The variable that is measured during the study
Define independent variable
The variable that is manipulated by the investigator
Define control group
A singular group of animals that does not receive the experimental treatment
Define treatment group
The animals that receive the experimental treatment
Name a statistical method that helps control variables by eliminating personal bias from the study
Randomization
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
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
True or False
For a sample that has a normal distribution, 95% of the data points will fall within +/- 2 SD
True
What is the difference between the confidence level and the p value?
The index of certainty that the difference is due to the experimental treatment
What factor is controlled by randomization?
Bias
Explain the difference between an experimental and a null hypothesis
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
In a normal distribution, what percentage of measurements fall between the mean and plus or minus 1 standard deviation
68%
In a normal distribution, what percentage of measurements fall between the mean and plus or minus 2 standard deviations
95%
In a normal distribution, what percentage of measurements fall between the mean and plus or minus 3 standard deviations
99%
What is the definition of standard deviation
Measure of the dispersion of data
What is the definition of null hypothesis
A statement that there is no difference between the means of the two groups
What is the definition of variable
Anything that can potentially affect the results of the study
What is the definition of p value
The probability that the observed difference happened by chance alone
What is the definition of confidence value
Index of certainty
What is the definition of sample size
The number of experimental units in a group
Information based on reported examples is known as: A- Erroneous B- Practical C- Anecdotal D- Biased
C- Anecdotal
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
C- In any distribution, the same percentage of data points will fall within one standard deviation from the mean
Details of the assessed treatment(s) and measurements are describes by the: A- Experimental hypothesis B- Research question C- Study design D- Statistical analysis
C- Study design
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
B- Generality
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
B- It represents anything that can affect the results of a study
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
D- A science textbook
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
B- Null hypothesis
A(n) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is an assumption evaluated by research. A- Hypothesis B- Objective C- Observation D- Theory
A- Hypothesis
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
D- Conclude that there is no significant difference between groups
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
C- There is a 95% probability that the difference is real
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
D- Power
The confidence level is an index of: A- Certainty B- Accuracy C- p-value D- Average value
A- Certainty
A(n) \_\_\_\_\_\_\_ is an assumption evaluated by research. A- Hypothesis B- Observation C- Theory D- Objective
A- Hypothesis
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
D- Nonexperimental variable
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
A- Influence on study data by investigators or conditions
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
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
