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Research Methods > Week 5 > Flashcards

Week 5 Flashcards

1
Q

What is experimental research?

A

Designed to control for confounding variables
based on logic, changes are systematically introduced, “cause & effect”

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2
Q

Extraneous variables

A

any factor NOT related to the purpose of the study
may affect dependent variables

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3
Q

In experimental research, the control group may receive what?

A

standard treatment, no treatment/”wait and see”, placebo treatment

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4
Q

What is the gold standard of experimental research?

A

RCT

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5
Q

three essential components of true experimental designs

A
  1. independent variable “manipulated” by the experimenter
  2. Include a control or comparison group
  3. participants are randomly assigned to groups
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6
Q

What is random assignment?

A

** not the same as random sampling **
each participant has EQUAL chance of being assigned to any group
helps control for extraneous variables or prognostic indicators
should result in homogeneous groups at baseline (not IV)

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7
Q

Random Assignment Strategies

A

Simple random assignment
Block random assignment
Stratified random assignment
Cluster random assignment

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8
Q

What is simple random assignment

A

coin flip
every person has an equal chance to be in either group
can have UNEVEN groups

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9
Q

what is block random assignment

A

envelopes
divided equally into “blocks”
assures groups will be evenly distributed by group or treatment sequence

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10
Q

what is stratified random assignment

A

used when certain characteristics (attributes) may be confounding

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11
Q

what is cluster random assignment

A

ex: 3 different hospitals
clusters are formed, and each cluster is randomly assigned a treatment
-all members of a cluster get the same treatment

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12
Q

Concealed Allocation

A

the researchers do NOT know group assignment

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13
Q

types of Experimental Design Validity

A

statistical conclusion validity
internal validity
construct validity
external validity

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14
Q

statistical conclusion validity

A

“is there a relationship between the independent and dependent variables?”

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15
Q

Internal Validity

A

“is there evidence of a causal relationship between independent and dependent variables?”

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16
Q

Construct Validity

A

“to what constructs can results be generalized?”

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17
Q

external validity

A

can the results be generalized to other persons, settings, or times?

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18
Q

assumption of causality requires three components:

A
  1. Temporal precedence
  2. Covariation of cause and effect
  3. no plausible alternative explanation
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19
Q

temporal precedence definition

A

cause precedes effect

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20
Q

covariation of cause and effect definition

A

outcome ONLY occurs in the presence of the intervention

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21
Q

No plausible alternative explanation definition

A

consider confounding variables

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22
Q

Internal Validity Internal Threats

A

History, Maturation, Attrition, Testing, Instrumentation, Regression to the mean, Selection, and Social Interaction

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23
Q

Internal Threat: History

A

an unrelated event influences outcomes - did something else happen between measurements?
ex: caffeine

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24
Q

Internal Threat: Maturation

A

Passage of time affects DV

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25
Q

Internal Threat: Attrition

A

“experimental mortality”
-patients drop out
diet to restrictive?
diet not working?

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26
Q

Internal Threat: Testing

A

Collection data changes the response

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27
Q

Internal Threat: Instrumentation

A

a measuring instrument (or measurer) changes over times

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28
Q

Internal Threat: Regression to the mean

A

extreme scores become less extreme over time

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29
Q

Internal Threat: Selection

A

Problematic when participants self-select groups
addressed with random assignment

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30
Q

Internal Threat: Social Interaction

A
  • diffusion/imitation
  • compensatory equalization
  • compensatory rivalry
  • demoralization
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31
Q

Internal validity social threats

A

Diffusion/imitation, compensatory equalization, compensatory rivalry, demoralization

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32
Q

Social threats: Diffusion/imitation

A

participants in control group changed behavior to match experimental group

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33
Q

Social threats: Compensatory equalization

A

Researchers treat participants in control group differently to make up the difference
-researcher feels bad for a group

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34
Q

Social threats: compensatory rivalry

A

participants in control group look at a LOT of puppy photos to increase happiness

35
Q

Social threats: demoralization

A

participants in the control group “give up”

36
Q

Ruling Out threats to internal validity

A

random assignment and blinding

37
Q

types of blinding

A

single = patient doesn’t know
double = patient + PT OR patient + assessor
triple = extremely rare

38
Q

Threats to Construct validity

A

operational definitions, comprehensive measurements, time frame, multiple treatment interactions

39
Q

Threats to external validity

A
  • influence of selection
  • influence of settings
  • influence of history
40
Q

influence of selection definition

A

age, gender, diagnosis

41
Q

Influence of settings definition

A

RCT vs Pragmatic clinical trials

42
Q

Influence of history

A

older studies still have value!

43
Q

with Noncompliance participants may:

A
  • refuse the assigned treatment after allocation
  • cross over to another group
  • be compliant with assigned treatments
  • withdraw from the study
44
Q

Missing Data

A
  • needs to be accounted for throughout trial
  • concerning if > 20%
  • a problem if related to treatment
  • drop-outs? switch-overs?
45
Q

Per Protocol Analysis

A

analyze only those who completed study

46
Q

Intention-to-Treat (ITT) Analysis

A

-analyze in the group that they were assigned to
-imputation: estimating missing data values

47
Q

Researchers can minimize bias using

A

randomization, concealed allocation, blinding, and ITT

48
Q

Internal threats are

A

INSIDE the study (methodology)

49
Q

External threats are

A

OUTSIDE the study (generalizing)

50
Q

True Experimental design is

A
  1. IV “manipulated” by researcher
  2. at least two comparison groups
  3. subjects randomly assigned
51
Q

Quasi-experimental designs

A
  • may lack randomization
  • may lack comparison group
  • may lack both
52
Q

types of experimental designs

A
  • between-subjects design
  • within-subjects
  • factorial
53
Q

Between-subjects design

A

assigned to independent groups

54
Q

Within-subjects design

A

participants act as their own controls

55
Q

Factorial design

A

how we describe designs that have 2+ IV
- two-way design, 3x3 factorial design

56
Q

One-way Designs

A

only 1 IV
AKA single-factor designs
Pretest-posttest control group design
- used to compare 2 or more groups formed by random assignment

57
Q

Pretest-Posttest control group design

A
  • both groups are measured before and after treatment
  • cause and effect
  • internal validity is strong
58
Q

Posttest-only Control Group Design

A
  • similar to pretest-posttest control group, but no pretest is administered to either group
  • used when pretest is impractical, contraindicated, or potentially reactive
  • internal validity is strong
59
Q

what should we assume about the posttest-only control group design

A

assume groups are equivalent due to random assignment
best with large group of subjects

60
Q

Factorial designs for independent groups

A

Two-way factorial design
Randomized block design

61
Q

Two-way factorial design

A
  • incorporates two or more independent variables
  • randomly assigned to various combinations of the levels of the variables
62
Q

Randomized block design

A
  • 1 IV is not randomized
  • attribute variable
  • blocked
63
Q

Benefits of factorial designs for ind groups

A

gives you information beyond what a single-factor (one-way) design would

64
Q

Challenges of factorial designs for ind groups

A
  • Larger sample
  • results of analysis can be difficult to interpret
65
Q

Naming Factorial Designs definition

A
  • described according to the number of IVs
  • number of levels within each factor
66
Q

Designs for Repeated Measures

A

same people in each level of the IV
- within-subject design

67
Q

One-way (aka single-factor) repeated measures design

A
  • subjects are exposed to all levels of the IV
  • there is no control group
68
Q

Effects of Repeated Measures

A
  • practice effects
  • carryover effects
  • order effects
69
Q

practice effects definition

A

the more you do something, the more efficient you become

70
Q

carryover effects definition

A

the effects of the first rx still present when second rx is introduced

71
Q

Order effects definition

A

use of Latin Square as a possible solution of order effects

72
Q

Crossover designs

A
  • participants are randomized to a treatment sequence
  • used to control for order effects
  • considerations for washout period
73
Q

Two-way (multi-factor) repeated measures design

A

all IVs are “repeated” or “within-subject”

74
Q

Experimental designs can be _____

A

between-subject, or within-subject, or mixed

75
Q

a one-way pretest-posttest control group design is the _______

A

most basic structure of a RCT

76
Q

A week before the end of the study, all employees are told that there will be layoffs. The participants are stressed on the date of the post-test, and performance may suffer.

What type of internal threat?

A

History

77
Q

What type of internal threat?

Most participants are new to the job at the time of the pre-test. A month later, their productivity has improved as a result of time spent working in the position.

A

maturation

78
Q

What type of internal threat?

In the pre-test, productivity was measured for 15 minutes, while the post-test was over 30 minutes long.

A

Instrumentation

79
Q

What type of internal threat?

Participants showed higher productivity at the end of the study because the same test was administered. Due to familiarity, or awareness of the study’s purpose, many participants achieved high results.

A

Testing

80
Q

What type of internal threat?

Low-scorers were placed in Group A, while high-scorers were placed in Group B. Because there are already systematic differences between the groups at the baseline, any improvements in group scores may be due to reasons other than the treatment.

A

Selection bias

81
Q

What type of internal threat?

Because participants are placed into groups based on their initial scores, it’s hard to say whether the outcomes would be due to the treatment or statistical norms.

A

Regression to the mean

82
Q

What type of internal threat?

Groups B and C may resent Group A because of the access to a phone during class. As such, they could be demoralized and perform poorly.

A

Social interaction

83
Q

What type of internal threat?

20% of participants provided unusable data. Almost all of them were from Group C. As a result, it’s hard to compare the two treatment groups to a control group.

A

Attrition bias

Research Methods (5 decks)

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