The phrase "a valid effect" is correct and usable in written English.
It can be used when discussing the legitimacy or acceptability of an outcome or result in various contexts, such as scientific, legal, or analytical discussions.
Example: "The study demonstrated that the new treatment had a valid effect on reducing symptoms in patients."
Alternatives: "a legitimate impact" or "a credible outcome."
A valid effect estimate indicating a higher rate with tiotropium means that tiotropium increases risk more than LABA but both drugs could be either increasing or decreasing risk.
To ensure a valid effect estimate, this should be based on a high quality study or on meta-analysis if enough high quality data is available to carry out such analysis.
When assessing attributable fraction, the estimate of exposure should be accurate in terms of giving a valid effect estimate, but it does not need to be representative of the entire population.
There is a modicum of support for the use of oxytocin as an adjunct to antipsychotic drugs [ 11] but whether this latest finding is a valid effect remains a matter of conjecture.
Insulin production was earlier hypothesized as a valid effect of VA administration in diabetic condition [ 13] and insulin is known to favour tissue storage of the fuel molecules including TGs.
For a valid effect to have been demonstrated in Greer et al.'s [ 11] more modest sample of 57 women with early breast cancer, effects of a fighting spirit would have to be even much stronger than most known biological factors or treatments.
Our analyses, however, do not support other criteria for a valid subgroup effect.
Good evidence of a valid subgroup effect results from testing few a priori hypotheses based on strong biological rationale.
Assuming this bias to be constant, we did not attempt to adjust for bias in our analyses, and we do not claim to estimate a valid treatment effect of the opioids under review.
Exposure estimates with minimal measurement error are necessary to produce valid effect estimates.
Such mainly individual and educational interventions are better suited for evaluation in RCTs enabling internally valid effect estimates.
