The phrase "ambiguous effects" is correct and usable in written English.
It can be used when discussing outcomes or results that are unclear or open to multiple interpretations.
Example: "The study revealed ambiguous effects of the new drug on patient recovery times, leaving researchers puzzled."
Alternatives: "unclear outcomes" or "vague results".
Market-related variables and population density have ambiguous effects.
Interestingly, we show that widespread adoption of such loans has ambiguous effects on the homeownership rate and household welfare.
First, there are strong positive impacts of TFP (without and with human capital) on manufacturing employment, as well as ambiguous effects of labour productivity on employment.
While theoretical predictions point to possible improvements in health, consumption and ambiguous effects on labor supply, there are few empirical studies that used robust designs.
Of all the historical forces that have worked upon its diverse peoples in the past century — maritime trade, imperialism, development, and despotism — the economy and the culture of globalization may turn out to have the most profoundly ambiguous effects.
Tree species composition, age difference with surrounding stands, stand area, stand openness and soil characteristics are secondary to the tree size variables in explaining the defoliation intensity, and often had ambiguous effects.
With competitive interaction, however, price discrimination has an ambiguous effect on both profits and consumer welfare.
And in both Australia and Britain, the gun restrictions had an ambiguous effect on other gun-related crimes or deaths.
Studies ignoring dynamic departure-time behaviour show an ambiguous effect of transit improvements to the city.
Ammonia levels in the range studied had an ambiguous effect on T. angustifolia.
The highly publicized departure of American companies from South Africa is having a far more ambiguous effect than advocates of such divestment might have hoped for.
