Estee posted on Wednesday, October 16, 2013 - 6:22 am
I tested a mediation model. The indirect effect was bootstrapped. The 95% confidence limit was [.000, .038]. According to literature, an indirect effect is considered sig. if the CI does not include/cross zero. Is the .000 showed in the results really equal to zero or it may be for example.0001 ? so, how to confirm whether the 95% confidence limit [.000, .038] is sig or not?
I would count that as non significant even if the value was .0001. With so many tests being performed, I would be conservative.
Joao Garcez posted on Friday, March 13, 2015 - 10:27 am
I was wondering something similar. I have a non-significant indirect effect (b = -.019, p>.05) with the following bc bootstrap 95% CI: ( -.047 - .002 ).
Is a value of .002 considered to be equal to zero?
Also, when values in the lower and upper bound have opposite signs like the one above, does it mean something? The path above is negative with a positive value in the CI. Does it mean is non-significant?
Related to the above: I run a single-level mediation model as specified below.The indirect effect (a1d1b2) based on z-test does not become sign (p = .112), but the 95% CI does not include 0 (.008-.394). If I run the respective process model in SPSS, the CI does also not include 0, showing significance. Bootstrapping is a more powerful test, but any idea how I should report these findings? My n is 146 and the CIs asymmetric.
Many thanks, Kristin
USEVARIABLES = WFBS Health ALQ FSSB sexI1 ageI1 child; ANALYSIS: TYPE = GENERAL; ESTIMATOR = ML; BOOTSTRAP = 5000; MODEL: Health ON FSSB (b1); Health ON WFBS (b2); Health ON ALQ (cdash); ! direct effect of X on Y FSSB ON ALQ (a1); WFBS ON ALQ (a2); WFBS ON FSSB (d1); Health on sexI1 ageI1 child; MODEL CONSTRAINT:
Thank you for this Bengt and sorry for the delay in responding. Yes, I meant (.008,.394) and just used the "-" to indicate the boundaries of the CI (I am aware that this is not normally done so, so sorry). Would you mind advising me on the best way to do bootstrapping in multi-level analysis as I think MPlus does not (yet) offer this feature and hint me towards a relevant paper/article etc. where I can read up on this? I heard various approaches but unsure which to pursue.