Johns Hopkins Nursing Evidence-Based Practice Thrid Edition: Model and Guidelines

6 Evidence Appraisal: Research 131

Table 6.8 Quality Rating for Quantitative Research Evidence

Grade Research Evidence

A: High Consistent, generalizable results; sufficient sample size for study design;

adequate control; definitive conclusions; consistent recommendations

based on comprehensive literature review that includes thorough reference

to scientific evidence

B: Good Reasonably consistent results; sufficient sample size for the study

design; some control; fairly definitive conclusions; reasonably consistent

recommendations based on fairly comprehensive literature review that

includes some reference to scientific evidence

C: Low or

Major flaw

Little evidence with inconsistent results; insufficient sample size for the

study design; conclusions cannot be drawn

Grading the Quality of Research Evidence

The large numbers of checklists and rating instruments available for grading the

quality of research studies presents a challenge to an EBP team. Tools to appraise

the quality of scientific evidence usually contain explicit criteria with varying

degrees of specificity according to the evidence type. EBP teams often do not

have the comprehensive knowledge of methodological strengths and limitations

required to interpret these criteria. An EBP team needs to involve someone with

knowledge of interpretation of research and statistics—often a nurse with a doc-

toral degree—to guide them through the process.

Because the development of any EBP skill set is evolutionary, the JHNEBP model

uses a broadly defined quality rating scale. This provides structure for the EBP

team yet allows for the application of critical-thinking skills specific to the team’s

knowledge and experience. The application of this scale, shown in Table 6.8,

accommodates qualitative judgments related to both research and nonresearch

evidence.

Judgments of quality should be relative. At any given point in the process, each

individual or group applies the same interpretation to the body of evidence.