Temporal Design Considerations
-
Upload
kevin-cummins -
Category
Data & Analytics
-
view
48 -
download
2
description
Transcript of Temporal Design Considerations
![Page 1: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/1.jpg)
1
Longitudinal Design Considerations
Kevin CumminsAddictions Research Seminar
University of California, San Diego
August 29, 2006
![Page 2: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/2.jpg)
2
Objective
• Provoke a discussion about the needs and realities of designing and executing a longitudinal research project.
![Page 3: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/3.jpg)
3
Outline
• Introduction
• Basic Structural Variations in Longitudinal Studies
• Considerations in Temporal Design
• Conclusion
• Discussion
![Page 4: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/4.jpg)
4
Longitudinal Studies
• Defining feature: outcome variables measured on more than one occasion.
• Fundamental statistical feature: measurements will be correlated.
![Page 5: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/5.jpg)
5
Cross-sectional Data
From Frees 2005
![Page 6: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/6.jpg)
6
Longitudinal Structure Visualized
From Frees 2005
![Page 7: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/7.jpg)
7
Benefits
• Attrition bias• Logistic complexities
and expense• Delayed results
• Dynamic relationships revealed.
• Improved estimation efficiency.
• Provide descriptions of individual development patterns.
• Considered helpful in establishing causation.
Drawbacks
![Page 8: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/8.jpg)
8
Evidence for Causality
• Appropriate correlations/association
• Consistency in various environments• Specificity (cause leads to a single effect)• Dose-Response• Biological plausibility
• Temporality (cause precedes effect)
• Experimental evidence (causality tested)
![Page 9: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/9.jpg)
9
Outline
• Introduction
• Basic Structural Variations in Longitudinal Studies
• Considerations in Temporal Design
• Conclusion
• Discussion
![Page 10: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/10.jpg)
10
Experimental Longitudinal Studies (Most RCTs)
• Gold standard
• Efficiency and effectiveness require thoughtful treatment assignment and measurement regime
• Interpretation often limited by the sampling frame and the non-representative clinical environments
![Page 11: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/11.jpg)
11
Basic Experimental Designs
• Classic
• Classic with baseline
• Classic with longitudinal follow-up
• Factorial
• Cross-over design
• Solomon design
![Page 12: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/12.jpg)
12
Observational Longitudinal
• Can provide developmental description of phenomenon.
• Can provide correlation, consistency, dose-response, and temporality evidence of causation.
![Page 13: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/13.jpg)
13
Issues in Longitudinal Studies
• Period Effects
• Cohort Effects
• Measurement Effects
![Page 14: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/14.jpg)
14
Period Effect
![Page 15: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/15.jpg)
15
Cohort Effect
![Page 16: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/16.jpg)
16
Multiple Cohort Design
• Designs that follow multiple age cohorts through the same developmental time frames.
![Page 17: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/17.jpg)
17
What’s Going On?
![Page 18: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/18.jpg)
18
Detecting Period Effect
![Page 19: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/19.jpg)
19
Measurement Effect
![Page 20: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/20.jpg)
20
First Considerations
• Do you design for:• Evidence of causation,• Period effects,• Cohort effects,• Measurement effects?
![Page 21: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/21.jpg)
21
Outline
• Introduction
• Basic structural variations in longitudinal studies
• Considerations in temporal design
• Conclusion
• Discussion
![Page 22: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/22.jpg)
22
Analysis of Longitudinal Data: The Integration of Theoretical Model,
Temporal Design, and Statistical ModelLinda M. Collins
The Methodology Center andDepartment of Human Development & Family Studies
Penn State
Presented at the CALDAR Summer Institute, Los Angeles, CA August 14, 2006
Much of this talk comes from Linda Collin’s work
![Page 23: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/23.jpg)
23
Take Home from Collins 2006
• Ideal longitudinal research should be characterized by a tight integration of:
1) a well articulated theoretical model,
2) an appropriate temporal design,
3) and a statistical model that operationalizes the theoretical model.
![Page 24: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/24.jpg)
24
Theoretical Model of Change• General shape• Periodicity• Function of
– Calendar time/age/stage– Another changing variable– Or self-regulating
• Covariates– Time-invariant– Time-varying
• Is relation with covariates time-varying?• What are the magnitudes of the various patterns?• Is the response variable quantitative or qualitative?
![Page 25: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/25.jpg)
25
Temporal Design
• Timing, frequency, spacing of observations in a longitudinal study
• What makes a good temporal design?
– It provides a clear view of the change phenomenon of interest and articulation of aspect of interest.
![Page 26: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/26.jpg)
26
Comparison Features
• Property– Overall value/Magnitude– Extreme value– Delay in response
– Rate of change– Final level
– Delay in response– Overall Functional Form
• Summary Measure– Mean or AUC– Max/Min– Time to max/min or
change point
– Regression coef.
– Final value/relative difference
– Time to threshold– Linear/Nonlinear/Semipa
rametric statistical model
![Page 27: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/27.jpg)
27
Temporal Design
• Should be chosen on basis of theoretical model• Can’t observe change that occurs
– Before study begins– After study concludes– Between observations
• More frequent measurement called for when– Change is rapid– Curvilinear response (min. 4-5 time points)
• Timing may be critical when– Periodicity– Important event expected
![Page 28: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/28.jpg)
28
Pattern vs. Grain
• Other effects of using a measurement interval that is too wide:
– Important complexities of growth curves may go undetected
– Cannot detect important effects– Cannot model mediation properly– Oversimplify change processes and their relations
with other processes– Entire stages may be missed from stage-sequential
models, and rates of transitions may be inaccurate
![Page 29: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/29.jpg)
29
Get More Time Points
– When designing studies, choose the measurement interval in relation to the characteristics of the phenomena of interest
• If they are fast-moving, use a short interval
• If they are slow-moving, a longer interval is OK
– In most cases, this will lead to consideration of a shorter measurement interval
![Page 30: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/30.jpg)
30
Yeah, Right…
• Problems with more frequent measurement:– Available resources– Logistical difficulties– Measurement effects
![Page 31: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/31.jpg)
31
Temporal Design: Collins’ Note
• The choice of measurement interval should always be justified on scientific grounds
• Logistical considerations play a role, but any write-up should show that the design is a reasonable one given the phenomena of interest
![Page 32: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/32.jpg)
32
Outline
• Introduction
• Basic Structural Variations in longitudinal studies
• Considerations in Temporal Design
• Conclusion
• Discussion Match Good Temporal Design to Good Data Design
![Page 33: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/33.jpg)
33
Data Formats for Longitudinal Studies
Long Form
Wide Form
Subject ID Tx Response0 Response22 Response34 Response50 Response51 Response741 1 0.07 0.95 0.91 . . .2 2 0.89 0.93 0.47 . 0.493 1 0.28 . . . . .4 2 0.30 . 0.49 . 0.18 .
Time (days) Subject ID Tx Response0 1 1 0.0722 1 1 0.9534 1 1 0.910 2 2 0.8922 2 2 0.9350 2 2 0.4774 2 2 0.490 3 1 0.2822 3 1 0.050 4 2 0.3034 4 2 0.4951 4 2 0.18
![Page 34: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/34.jpg)
34
Benefits of Long Format
• Write syntax once!
• Recognize temporal inconsistencies quickly
• Take advantage of contemporary analysis techniques. Distinct “waves” not necessary
• Easy to create a wide file from long format, but not always vise versa
![Page 35: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/35.jpg)
35
Outline
• Introduction
• Basic Structural Variations in longitudinal studies
• Considerations in Temporal Design
• Conclusion
• Discussion
![Page 36: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/36.jpg)
36
Collins’ Concluding Remarks
Two comments I’ve heard when I talk about temporal design:
(1) EVERYBODY PAYS ATTENTION TO TEMPORAL DESIGN ALREADY
How many research reports in journal articles, or research proposed in grant proposals, justify the temporal design on anything but logistical grounds?
![Page 37: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/37.jpg)
37
Collins’ Concluding remarks
Two comments I’ve heard when I talk about temporal design:
(2) HOW CAN I BE EXPECTED TO FIND THE RESOURCES TO CARRY OUT THE IDEAL TEMPORAL DESIGN?
Usually you can’t, but it is still useful to articulate the ideal.
![Page 38: Temporal Design Considerations](https://reader036.fdocuments.in/reader036/viewer/2022070323/5597e0181a28ab58388b4852/html5/thumbnails/38.jpg)
38
Outline
• Introduction
• Basic Structural Variations in longitudinal studies
• Considerations in Temporal Design
• Conclusion
• Discussion