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OCR for page 103
APPEND LX A:
TECHNICAL COMMENTS ON SURVEY PLANNING
AND SURVEY DES ION LIMITATIONS
The following procedure is proposed for continuing assessments of the
design implications of specific uses of survey data ant for identifying
limitations in survey design for proposed uses.
PURPOSE -- IDENTIFICATION OF DESIGN CHANGES NEEDED BY EXAMINATION OF
. . . . .
~ ISTING SURVEY DESIGN
Decisions about what survey design changes are needed to permit a
specified use for the survey data can be made by first asking: Can the
specified use be accomplished within the existing design? If not, why
not?
This permits the specific identification of constraints on the
specified data use under examination that arise from the existing survey
design. Answers to '~by not" yield identification of changes in survey
design that would eliminate existing constraints.
The end product would be the identification of design changes
required (if any) to eliminate the existing constraint on the data use
and thus permit that use or a clear decis ion that no change in survey
des ign would permit that use .
PROCESS -- A SERIES OF STEPS Tat PROVIDE To INFORMATION NEEDED FOR To
CONTINUING ASSESSMENT OF To DESIGN IMPLICATIONS OF SPECIF IC USES FOR
SURVEY DATA AND FOR IDENTIFYING T~ LIMITATIONS IN SURVEY DESIGN FOR
PROPOSED USES
· What is the stated purpose of the survey?
· What in the specific use to be examined?
· For further definition of that use, what action arises from it?
- Program action?
Referral to another data base for additional information?
Development of a hypothesis to be tested in another data
set?
- Development of a hypothesis to be tested by planned
experiment?
OCR for page 104
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· What precise information is required for the scientific analyses
required before this action?
· What are the present cons traints to making those scientific
analys es ?
-- Is the existing design competent to permit these required
analyses? If not, why not?
-- Is there suf ficient scientific understanding to permit
interpretation of data relevant to this use ? Knowledge of
requirements? Knowledge of biologically acceptable
concentrations of contaminants or toxicants ? Knowledge of
physiologic response to dietary deficiencies or excesses?
In sum: Is the use fees ib le ?
In sum: Is a design change required for this use?
· What design changers) may be required for this use?
SAMPLING DESIGN/SUBJECT DESCRIPTORS
· Need for additional information/descriptore for class if ication
purpos es .
· Inadequate n in the cells that would be used in analysis.
· Total survey population, or population included in an analytic
cell, is not sufficiently representative of the U. S. population or
populat ion group .
In sum: What are the impl ications of these for changes on sub ject
descriptors to be collected and on design of sampling?
UNRELIAB IL ITY OF DATA ~ D IETARY OR OTHER ~
.
· Imprecision of data due to misreporting.
· Imprecision of data due to food composition tables.
· Imprecision of data due to inadequate description of foods.
In sum: What are the implications of these for changes in des ign of
s urvey ins truments ?
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— 105 ~
INTRAINDIVIDUAL VARIABILITY (IN DIETARY OR OTHER DATA)
-
In sum: Wha~c i8 the design approach (e.g., replication of tata)
needed? Can it be us et within the framework of a survey?
INTERINDIVIDUAL VARIABILITY (VARIATION FROM EFFECTS NOT CONTROLLED IN
STATISTICS ISIS)
· Variability associated with independent effects.
· Var lab it ity assoc later with nonindependent e f fee ts .
In sum: What is the des ign impl ication of need to control for other
sources of variation -- for descriptors to be collected and
for sample size? Is statistical control possible?
T IME:L INKS S
· Does the use depend on rapid turnaround?
In sum: What des ign changes would provide required
turnaround t ime ?
GENERAL SUMMARY -- PROCESS
(1) Is the use feasible to implement?
If not, stop.
2) Is a design change required for this use? If not, ~ top.
3 ~ What des ign changes are required for this use ?
Describe .
OCR for page 106
Representative terms from entire chapter:
des ign
