Table 2Distribution of the studies' quality* (94 studies)

Quality MeasuresMeanStandard DeviationMedian
Study question clearly focused and appropriate4.690.735
Clear definition of exposure3.960.654
Clear definition of the primary and secondary outcomes4.410.654.5
Sampling of study population3.340.813
Statistical analysis: assessment of confounding attempted3.611.114
Adjustment for the effects of various factors2.891.623.5
Statistical methods3.700.944
Measure of effect for outcomes3.661.114
External validity3.480.974
Total scores37.766.4038

Maximum possible score of 5; total of 50 for each study

From: 3, Results

Cover of Nurse Staffing and Quality of Patient Care
Nurse Staffing and Quality of Patient Care.
Evidence Reports/Technology Assessments, No. 151.
Kane RL, Shamliyan T, Mueller C, et al.

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