Causality

• several broad categories of research questions are relevant to EBN practice - questions about intervention, diagnosis, and assessment, prognosis, etiology/harm, and meaning or process

• more on leaning on cause and effect

• causes not deterministic but rather are probabilistic

Counterfactual model

• is what would happened to the same people exposed to a causal factor if they simultaneously were not exposed to the causal factor

• Effect : represents the difference between what actually did happen with the exposure and what would have happened without it

Criteria for causality

1. Temporal : cause must not precede effect in time

2. relationship : empirical relationship between the presumed cause and the presumed effect

3. No confounder : relationship cannot be explained as being caused by a third variable

4. Coherence: involves having similar evidence from multiple sources

5. Consistency: involves having similar levels of statistical relationship in several studies

6. biological plausibility : evidence from laboratory or basic physiologic studies that a causal pathway is credible

Experimental design

• researchers are active agents, not passive observers

• isolating phenomena and controlling the conditions under which they occurred

• considered the gold standard for yielding reliable evidence

Experimental design characteristics:

1. manipulation : researchers does something to at least some participants

2. control: researchers introduces control over the research situation

3. randomization: researchers assigns participants to a control or expiremental condition on a random basis

Patient-centered intervention

• used to enhanced treatment efficacy by taking people’s characteristic or needs into account

• each person receives an intervention customized to certain characteristics, such as demographic traits or cognitive factors

Control group

• refers to a group of participants whose performance on an outcome is used to evaluate the performance of the treatment group on the same outcome

• receives no treatment at all, merely observed with respect to performance on the outcome

Placebo / pseudo intervention

• have no therapeutic value

• are used to control for the nonpharmaceutical effects of drugs, such as the attention being paid to participants

attention control group

• used when they want to rule out the possibility that intervention affects are caused by the special attention given to those receiving the intervention rather than by the actual treatment content

randomization

• assigning participants to treatment conditions at random

• means participant have an equal chance of being assigned to any group

• Randomization principle

  • random assignment of people to one group or the other is designed to perform this equalization function

  • there is no guarantee that the group will be equal

• Basic Randomization

  • Straightforward randomization procedure, for a two-group design, is to simply allocate each person as they enroll into a study on a random basis.

  • starting with a known sample size and then prespecifying the proportion of subjects who will be randomly allocated to different treatment conditions

• Randomization procedures

  • the allocation process should be truly random

  • there must be strict adherence to the randomization schedule

  • involve allocation concealment that prevents those who enroll participants from knowing upcoming assignments

• randomization variants

  • offer advantages in terms of ensuring group comparability or minimizing certain biases

  • stratified randomization: randomization occurs separately for distinct subgroups

  • permuted block randomization: people are allocated to groups in small blocks ensure a balanced distribution in each block

  • urn randomization: group balance is continuously monitored and the allocation probability is adjusted when an imbalance occurs

  • randomized consent: randomization occurs prior to obtaining informed consent - Zelen design

  • Partial randomization - only people without a strong treatment preference are randomized - partially randomized patient

  • cluster randomization - involves randomly assigning cluster of people

Blinding

• used in RCT to prevent biases stemming from awareness

• involves concealing information from participants, data collectors, care providers, intervention agents, or data analysts to enhance objectivity and minimize expectation bias

• involves disguising or withholding information about participants’ status in the study

performance bias

• refers to systematic differences in the care provided to members of different groups of participants, apart from any intervention

detection

• concerns systematic differences between groups in how outcome variables are measured, verified, or recorded, is addressed by blinding those who collect the outcome data or, in some cases, those who analyze the data

open study

• blinding is not used

single-blind study

• blinding is used with only one group of people

double-blind study

• possible of masking two groups

factorial design

• involves manipulating only one independent variable and randomizing participants to different treatment groups’

• they permit us to test not only main effects but also interaction effects

crossover design

• involves exposing the same people to more than one condition

• type of within-subject design has the advantage of ensuring the highest possible equivalence among participants exposed to different conditions

• must be randomly assigned to different orderings of treatments

• they are inappropriate for certain research questions because of the problem of carryover effects

hawthorn effect

• placebo-effect caused by people’s expectation

Quasi-Experimental design

• called control trials without randomization in the medical literature, involve an intervention but lack randomization, the signature of a true experiment

• even lack a control group, is an intervention in the absence of randomization.

Nonequivalent control group pretest-posttest design

• involves 2 groups of participants, for whom outcome are measured before and after the intervention

Time series design

• data are collected over an extended period during which an intervention is introduced

statistical process control

• assess effects when they have collected data sequentially over a period of time before and after implementing an intervention or practice change

observational research

• researchers do not intervene by manipulating the independent variable, the study is nonexperimental

correlational design

• examine relationship between variables.

• a relationship or association between 2 variables, that is, a tendency for variation in one variable to be related to variation in another

• does not prove causation

retrospective design

• ones in which a phenomenon existing in the present is linked to phenomena that occurred in the past

• the researchers bein with the dependent variable and then examines whether it is correlated with one or more previously occurring independent variables

Prospective design / cohort design

• are costly than retrospective studies

• requires at least 2 rounds of data collection

Descriptive research

• aims to observe, describe, and document aspects of a situation as it naturally occurs and sometimes to serve as a starting point for hypothesis generation or theory development

Descriptive correlational research

• describe relationship among variables rather than support inferences of causality

Quiz answer

1. D blinding - neither mother nor baby

2. A. Comparison - what is counterfactual

3. D. Confounding variable - important in quanti to exert control

4. A. Crossover- alternate provision of implementation

5. B. Non-equivalent control design - not used used in RCT

6. C. Many variables of interest to nurse researchers cannot be experimented- true statement

7. B. Intervention - invariably of quasi

8. C. One-group pretest-posttest design - 70 participants were introduces to smoking cessation and look for baseline values after 3 months

9. D. Counterfactual - happened to effect and cause

10. D. Needs minimum oversight - not a characteristic of quali design

11. C. Selecting a scale - not an issue in quali researcher

12. B. How data to be collected- Design question in quali and quant

13. A. Emic perspective - ethnographer strive

14. B. Inferring- not part of descriptive phenomenology

15. B. Participatory action research- researchers work in vulnerable communities

16. B. All patients with covid-19 - a population

17. A. Ppl age 65 yo or younger - nrs. Study about falling of falling in community elders, which should be excluded

18. A. An army veteran in ncr- element in a population of military veteran in NCR

19. A. How representative the sample is of the population- key criterion on sample quality

20. D. Sampling bias- 50 percent and 20 percent of population

21. A. Convenience sampling- researcher use recruitment poster

22. D. Consecutive sampling- respondents are people who are going to ER

23. C. Quota- incorporate a strata

24. A. Sampling error- difference of sample values and population values

25. A. 75 percent- 200 - 50 = 75