What is the most serious threat to internal validity in non equivalent control group design?

1.The research design for a quantitative study involves decisions with regard to which of the following? Select all that apply

• Whether there will be an intervention
• What types of comparisons will be made
  
• How many times data will be collected
  

Feedback:

• The research design is the overall plan for answering research questions. In quantitative studies, the design designates whether there is an intervention, the nature of any comparisons, methods for controlling confounding variables, whether there will be blinding, and the timing and location of data collection.
  

2. Which of the following are key criteria for making causal inferences about the relationship between two variables? Select all that apply.

• Lack of temporal ambiguity about which variable occurred first.
  
• Statistical confirmation that a relationship between the two exists.
  
• The ability to rule out other factors as potential causes of the outcome.
  

Feedback: Key criteria for inferring causality include:

• (1) a cause (independent variable) must precede an effect (outcome)
  

• (2) there must be a detectable relationship between a cause and an effect
  

• (3) the relationship between the two does not reflect the influence of a third (confounding) variable.

3. An important function of a rigorous research design in a quantitative study is to have control over which of the following?

Confounding variables
Feedback: Key criteria for inferring causality include: (1) a cause (independent variable) must precede an effect (outcome) (2) there must be a detectable relationship between a cause and an effect (mediating) (3) the relationship between the two does not reflect the influence of a third (confounding) variable.

4. A true experiment requires which of the following? Select all that apply.

Control Intervention Randomization
Feedback: Experiments (or randomized controlled trials, RCTs) involve an intervention (the researcher manipulates the independent variable by introducing an intervention; control (including the use of a control group that is not given the intervention and represents the comparative counterfactual); and randomization or random assignment (with participants allocated to experimental and control groups at random to make the groups comparable at the outset).

5. The use of a random numbers table for assigning subjects to groups eliminates which of the following?

Selection threat Feedback: A selection threat reflects biases stemming from preexisting differences between groups; use of random assignment via a random numbers table eliminates selection threat.

6.Which of the following is invariably present in quasi-experimental research?

An intervention
Feedback:

• Quasi-experiments (trials without randomization) involve an intervention but lack randomization and, sometimes, a control group.
  

7. A one-group pretest-posttest design is an example of which of the following?

A quasi-experimental design
Feedback:

• Quasi-experiments involve an intervention but lack randomization and sometimes even a comparison group. Strong quasi-experimental designs introduce controls to compensate for these missing components.
  

8.A pretest is to a posttest as which of the following?

A baseline measure is to a final outcome measure
Feedback:

• In pretest-posttest designs, data are collected both before the intervention (at baseline) and after it (outcome). The control group can undergo various conditions, including no treatment; an alternative treatment; a placebo or pseudo intervention; standard treatment at different treatment doses; or a wait-list condition.
  

9.One weakness associated with cause-probing correlational research is which of the following?

Problem of self-selection into groups
Feedback:

• Correlational studies are susceptible to faulty interpretation because groups being compared have formed through self-selection (also called selection bias). When researchers study the effect of a cause they cannot manipulate, they use correlational designs that examine relationships between variables. A correlation is an interrelationship or association between two variables, that is, a tendency for variation in one variable to be related to variation in another. Correlations can be detected through statistical analyses.
  

10.Which of the following research designs is weakest in terms of the researcher's ability to establish causality?

Retrospective case-control
Feedback:

• Retrospective designs (case-control designs) involve collecting data about an outcome in the present and then looking back in time for possible causes.
  

11.If a researcher wanted to describe the relationship between women's age and frequency of performing breast self-examination, the study would be classified as which of the following?

Descriptive correlational
Feedback:

• Nonexperimental (observational) research includes descriptive research—studies that summarize the status of phenomena—and correlational studies that examine relationships among variables but involve no intervention or attempt to infer causal connections.
  

12.Studies that collect data at one point in time are called which of the following?

Cross-sectional studies
Feedback:

• Cross-sectional designs involve the collection of data at one time period, whereas longitudinal designs involve data collection at two or more times over an extended period.

13. A study that followed, over a 20-year period, 500 users and 500 non-users of oral contraceptives to determine if there were any long-term side effects would be which of the following?

Prospective study
Feedback:

• In prospective cohort designs, researchers begin with a possible cause, and then subsequently collect data about outcomes.
  

14. Constancy of conditions is often enhanced through which of the following?

Collect data at the same time every day
Feedback:

• Various external factors, such as the research environment, can affect outcomes. In carefully controlled quantitative research, steps are taken to minimize situational contaminants (i.e., to achieve constancy of conditions) so that researchers can be confident that outcomes reflect the influence of the independent variable and not the study context. Collecting data at the same time every day is an example of this.
  

15. Using homogeneity as a strategy for controlling confounding variables can reduce which of the following?

External validity
Feedback:

• External validity concerns inferences about whether relationships found for study participants might hold true for different people, conditions, and settings—in other words, generalizability.

16.Which of the following is the most effective method for controlling participant factors?

Randomization
Feedback:

• Randomization—the most effective method because it controls all possible confounding variables without researchers having to identify them.
  

17.In a case-control design, a frequently used method of controlling confounding variables is which of the following?

Matching of cases and controls on confounding variables
Feedback:

• Techniques for controlling subject characteristics include homogeneity (restricting participants to reduce variability on confounding variables); matching (deliberately making groups comparable on some extraneous variables); statistical procedures; and randomization—the most effective method because it controls all possible confounding variables without researchers having to identify them.
  

18.The researcher does not have to know in advance which confounding variables have to be controlled for which of the following procedures?

Randomization
Feedback:

• Techniques for controlling subject characteristics include homogeneity (restricting participants to reduce variability on confounding variables); matching (deliberately making groups comparable on some extraneous variables); statistical procedures; and randomization—the most effective method because it controls all possible confounding variables without researchers having to identify them.
  

19. The threat to internal validity that occurs when external co-occurring events or conditions affect outcomes is the threat known as which of the following?

History
Feedback:

• The history threat is the occurrence of events concurrent with the independent variable that can affect the outcome.

20. In an RCT, the most serious threat to internal validity typically is which of the following?

Mortality
Feedback:

• Mortality is the threat that arises from attrition in groups being compared. If different kinds of people remain in the study in one group versus another, then these differences, rather than the independent variable, could account for group differences in outcomes.
  

21. A study is internally valid to the extent that which of the following has taken place?

All alternative explanations to the independent variable as the cause of outcomes can be ruled out
Feedback:

• Internal validity is the extent to which it can be inferred that the independent variable is truly causing the outcome. Experiments (or randomized controlled trials, RCTs) involve an intervention (the researcher manipulates the independent variable by introducing an intervention; control (including the use of a control group that is not given the intervention and represents the comparative counterfactual); and randomization or random assignment (with participants allocated to experimental and control groups at random to make the groups comparable at the outset). Intervention fidelity helps to avert biases and gives potential benefits a full opportunity to be realized. A counterfactual is what would have happened to the same people simultaneously exposed and not exposed to a causal factor. The effect is the difference between the two. A good research design for cause-probing questions entails finding a good approximation to the idealized counterfactual.
  

22. In a nonequivalent control group design, the most serious threat to internal validity is which of the following?

Selection
Feedback:

• The selection threat reflects biases stemming from preexisting differences between groups. Selection bias is the most challenging threat to the internal validity of studies not using an experimental design (e.g., nonequivalent control group designs, case-control designs), but can be partially addressed using control mechanisms described in the previous section
  

23. The use of a diverse sample of study participants in multiple sites might affect which of the following?

The study's external validity
Feedback:

• External validity concerns inferences about generalizability—whether findings hold true over variations in people, conditions, and settings. Having a diverse sample of study participants in multiple sites would likely enhance the study's generalizability, and thus its external validity.
  

24. When participants' behaviors are affected not by the treatment per se but by their knowledge of participating in a study, interpretation of the findings is complicated by the influence of which of the following?

Hawthorne effect
Feedback:

• Hawthorne effect, in which various environmental conditions vary to determine their effect on worker productivity.
  

Which of the following can reduce the statistical conclusion validity of a study?

Low power
Feedback:

• Statistical power refers to the capacity to detect true relationships. Statistical power can be achieved in various ways, the most straightforward of which is to use a large enough sample. With small samples, statistical power tends to be low, and the analyses may fail to show that the independent variable and the outcome are related—even when they are, thus reducing statistical conclusion validity.
  

26. The nurse is designing a research study to assess the effectiveness of two wound healing dressings. What key design feature will be most important to address in this type of study?

Comparisons
Feedback:

• The key design feature would be to address the use of comparisons.
  

27. When addressing control of confounding variables, which of the following best describes the question to be answered by the researcher?

What other variables may influence the results?
Feedback:

• When addressing control of confounding variables, the researcher needs to answer the question, “What other variables may influence the results?”
  

28.Which of the following statements best illustrates causality?

Prolonged sun exposure is associated with higher rates of skin cancer.
Feedback:

• The statement, “Prolonged sun exposure is associated with higher rates of skin cancer” best illustrates causality.
  

29. Which of the statements below best illustrates the temporal criterion needed for a causal relationship?

Following vaccination for varicella, rates of varicella infection are lower.
Feedback:

• A cause must precede an effect in time. The answer “Following vaccination for varicella, rates of varicella infection are lower” best establishes that the suspected cause (vaccination) comes before the observed effect (decrease in varicella infection rates)..
  

Which of the following are distinctive characteristics of a true experimental design? Select all that apply.

• Intervention
  
• Control
  
• Randomization
  

Feedback:

• A true experimental design is characterized by intervention, control, and randomization.
  

31. Applying your knowledge of random assignment, which statement is correct?

Random assignment ensures that the study is a true experiment.
Feedback:

• Experimental designs involve placing participants in groups at random. Through randomization (or random assignment), every participant has an equal chance of being included in any group. Randomization is a critical characteristic of a true experimental study.
  

32. Which of the graphic representations illustrates a randomized experimental interventional design with pre- and posttest?

R O X O
Feedback:

• Experimental designs can be depicted graphically using symbols to represent features of the design. In these diagrams, the convention is that R stands for randomization to treatment groups, X represents receipt of the intervention, and O is the measurement of outcomes. So, for example, a pretest-posttest design would be depicted as follows: R O X O.
  

33. Which statement infers the advantage to using cross-over designs for quantitative research?

Enhances equivalence among participants exposed to different interventions.
Feedback:

• In crossover designs, people are exposed to more than one experimental condition in random order and serve as their own controls.
  

34. Quasi-experimental research designs lack what feature found in true experimental research?

Randomization
Feedback:

• Randomization is not seen in a quasi-experimental research design. Quasi-experimental studies may have control groups, pretests, and placebos.
  

35. Use of nonexperimental designs in research fulfills what purpose?

Describing
Feedback:

• A nonexperimental design in research fulfills the purpose of describing.
  

36. The nurse plans a study comparing the occurrence of anxiety disorders in military personnel deployed overseas with those who served strictly within the borders of the United States. What research design should be selected for this study?

Nonexperimental
Feedback:

• A nonexperimental design should be selected for this study. When researchers do not intervene by controlling the independent variable, the study is nonexperimental, or, in the medical literature, observational.
  

37.Cross-sectional designs work best under what research conditions?

Describing phenomena at a fixed point
Feedback:

• Cross-sectional designs work best with describing phenomena at a fixed point. Cross-sectional designs involve the collection of data at one time period.
  

38.The nurse wishes to study the opinions of high school students concerning the availability of health care services at XYZ High School during the past school year. What research design best fits with the study objective?

Cross-sectional study
Feedback:

• A cross-sectional study design would best fit with this study objective. Cross-sectional designs involve the collection of data at one time period, whereas longitudinal designs involve data collection at two or more times over an extended period. Cross-sectional designs are economical and easy to manage, and there is no need for inferring changes over time in this case. In nursing, most longitudinal studies are follow-up studies of clinical populations. Longitudinal studies are best for understanding trends over time.
  
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39. Which of the following situations illustrates control over an external confounding variable?

Using a script to relay information about the study.
Feedback:

• Use of a script to relay information about the study illustrates control over an external confounding variable-study context.
  

40.What is the strongest method of controlling for intrinsic (subject) factors?

Randomization
Feedback:

• The strongest method of controlling for intrinsic (subject) factors is randomization. It is the most effective method of controlling participants' characteristics.
  

41.What study design flaw may lead to a failure to achieve statistical significance?

Small sample size
Feedback:

• With small samples, statistical power tends to be low, and the analyses may fail to show that the independent variable and the outcome are related—even when they are.
  

42. Using your knowledge of threats to internal validity, which research design will be most susceptible?

Correlational
Feedback:

• A correctional research design is most susceptible to threats to internal validity.
  

43. Which situation best reflects “attrition” in quantitative research?

Control group subjects drop out of the study when their disease process does not improve.
Feedback:

• Mortality is the threat that arises from attrition in groups being compared. The most severely ill patients might drop out of the experimental condition because it is too demanding.
  

44. Which quantitative research design will most strongly support evidence-based practice?

Randomized Control Trial Design
Feedback:

• A randomized control trial design will most strongly support evidence-based practice. Randomized controlled trials are the most powerful designs for testing hypotheses of cause-and-effect relationships.
  

45. A review of research reveals two articles that have conflicting results. A national randomized controlled trial found that annual brain scans will allow early detection and treatment of brain cancers, reducing mortality by 65%. An international quasi-experimental trial reported no significant reduction in mortality with annual scans. Based on your review, propose the best recommendation.

Recommendations from the national study should be followed.

Feedback:

• Methodologically, the main design issue in quantitative studies is whether the research design provides the most valid, unbiased, and interpretable evidence possible. Indeed, there usually is no other aspect of a quantitative study that affects the quality of evidence as much as research design. RCTs are the “gold standard” for intervention studies (Therapy questions) because they yield the highest-quality evidence about the effects of an intervention. Therefore, the best recommendation would be to follow the recommendations from the national randomized controlled trial because it is more authoritative than the quasi-experimental trial.
  

46. A research proposal states that the objective is to, “explore the incidence of homeopathic health practices on Iowa Native Reserves in Oklahoma.” In describing the design to be used for conducting the study, the researchers plan to use a nonexperimental design. What can you conclude from this proposal?

This research may not be answered completely if a quantitative design is used.
Feedback:

• The research may not be answered completely if a quantitative design is used, because the research question is not amenable to quantitative research.
  

47. To study the effects of Healing Touch; what is the best choice to minimize confounding variables?

Offer another activity that gives similar time and attention to control group participants.
Feedback:

• The best way to minimize confounding variables is to offer another activity that gives similar time and attention to control group participants—known as a placebo. Otherwise, the participant's knowledge of not receiving a treatment may affect the study's results.
  

What is the most serious threat to internal validity?

What is the major problem with the nonequivalent control group design?

Which of the following is the primary threat to internal validity for nonequivalent Group designs?

Which design controls the most threats to internal validity?