# Slope is negative but confidence limits contain zero, how do I describe the effect?

I performed an ANCOVA on final height (height4) with initial height as a covariate.

Dependent variables:

ipc.gm = initial % cover of garlic mustard

fence = factor with 2 levels: Fence, Open

There was a significant interaction effect: ipc.gm*fence

An interaction plot shows that height4, corrected for initial height, increases with increasing ipc.gm, but only in Fence plots.

I used emtrends() to get the slope of each line:

> emtrends(model3, pairwise ~ fence, var = "ipc.gm")
NOTE: Results may be misleading due to involvement in interactions
$emtrends fence ipc.gm.trend SE df lower.CL upper.CL Fence 0.06585603 0.02670941 92 0.01280884 0.11890322 Open -0.02830168 0.03487092 92 -0.09755835 0.04095498 Results are averaged over the levels of: gm Degrees-of-freedom method: containment Confidence level used: 0.95$contrasts
contrast       estimate         SE df t.ratio p.value
Fence - Open 0.09415771 0.04201853 92   2.241  0.0274

Results are averaged over the levels of: gm


The "ipc.gm.trend" for Fence gives a positive slope of 0.0659, with a lower confidence limit of 0.0128 and an upper confidence limit of 0.1189.

The "ipc.gm.trend" for Open gives a negative slope of -0.0283, with a lower confidence limit of -0.0976 and an upper confidence limit of 0.0410.

Questions

1. When writing my paper, I will say that height4, corrected for initial height, increased with increasing ipc.gm at the Fence level. Do I back this up by reporting the positive slope, or confidence limits, or both?

2. For the Open level, the slope is negative but the confidence limits contain zero. Should I say that height4, corrected for initial height, decreased with increasing ipc.gm and back this up by reporting the slope? Or should I say that height4, corrected for initial height, was not affected by ipc.gm and back this up by reporting the confidence limits?