Gaining confidence with intervals: practical guidelines, advices and tricks of the trade to face real-life situations.


Confidence intervals
interval statistics
graphic representation
national surveys
Bayesian approach

How to Cite

Beaulieu-Prévost, D. (2010). Gaining confidence with intervals: practical guidelines, advices and tricks of the trade to face real-life situations. International Journal of Psychological Research, 3(1), 46–57.


Confidence intervals and measures of effect size are gradually becoming the standard way of reporting the results of statistical analyses in research articles, used instead of or in addition to p values. However, this shift in research practices barely affected teaching practices up to now. This paper is the third of a series written to serve as a general reference on the use of confidence intervals in quantitative social sciences. Its purpose is to provide guidelines, advices and useful tricks of the trade that will allow readers (a) to face most of the statistical problems emerging in real-life research settings and (b) to improve their understanding of confidence intervals and answer more efficiently their questions of interest. The first part of the article briefly introduces the basic elements of an approach based on confidence intervals: Calculations, interpretation, and hypothesis testing. The second part is an attempt to present some of the most important (but sometimes neglected) advanced issues concerning confidence intervals: Graphic representations, complex distributions, national surveys, the larger family of interval statistics (e.g., prediction intervals), and the Bayesian approach to probabilities.


Beaulieu-Prévost, D. (2006). From tests of statistical significance to confidence intervals, range hypotheses and substantial effects. Tutorials in Quantitative Methods for Psychology, 2, 11-19.

Beaulieu-Prévost, D. (2007). Statistical decision and falsification in science: Going beyond the null hypothesis. In B. Hardy-Vallée (Ed.). Cognitive decision-making: Empirical and foundational issues. Cambridge : Cambridge Scholar Publishing. [A previous version of the paper also appears at, page visited october 15th, 2009]

Beaulieu-Prévost, D. Professional web site: Statistical resources, [Online].

The work that is sent to this journal must be original, not published or sent to be published elsewhere; and if it is accepted for publication, authors will agree to transfer copyright to International Journal of Psychological Research. 

To give up copyright, the authors allow that, International Journal of Psychological Research, distribute the work more broadly, check for the reuse by others and take care of the necessary procedures for the registration and administration of copyright; at the same time, our editorial board represents the interests of the author and allows authors to re-use his work in various forms. In response to the above, authors transfer copyright to the journal, International Journal of Psychological Research. This transfer does not imply other rights which are not those of authorship (for example those that concern about patents). Likewise, preserves the authors rights to use the work integral or partially in lectures, books and courses, as well as make copies for educational purposes. Finally, the authors may use freely the tables and figures in its future work, wherever make explicit reference to the previous publication in International Journal of Psychological Research. The assignment of copyright includes both virtual rights and forms of the article to allow the editorial to disseminate the work in the manner which it deems appropriate. 

The editorial board reserves the right of amendments deemed necessary in the application of the rules of publication.