Our testing process begins by wearing all of the jackets in the field, having the same adventures that you will be having, whether that be cragging, skiing, backpacking or going to an outdoor winter festival with the family, all while evaluating each model, noticing what works and what doesn't. Often we will wear two or more contenders on the same adventure to compare them side by side, and we love to lend out our test products for others to try. Their feedback helps confirm ours. In all cases, we strive to produce a comparison review.
This means that there is no standard against which we test all these jackets; the jackets themselves are the standard. All scores and opinions discovered through our testing are expressed to you in comparison to the other competing products in the review. However, to make the best comparisons that we can, we often expand upon our field testing to conduct side-by-side controlled tests, which are described below.
Warmth
Most of our testing for this metric was conducted on adventures in the field, but to get the best idea of exactly which jackets are the warmest, we tested these side-by-side in temperatures down into the low 30s with windchills of near zero. We used them as terminal layers with just a t-shirt underneath so we could be sure to feel any drafts that got through. While these tests weren't performed in a lab, they were taken seriously and done in a systematic way.

Weight
To accurately compare weight, we measured each jacket on our independent scale immediately upon taking it out of the package. In instances where stuff sacks were included in the purchase, we included them in the overall weight of a jacket.
Water Resistance
To test these jackets for water resistance, we waited until the end of our testing period, so we could get a better idea of which products had a more durable DWR coating, as DWR does, in fact, degrade with time and use. We then tested them head-to-head by spraying them with a misting spray bottle, all over, to get an idea of how well the DWR coating performs in a drizzle or light rain. We graded based on the performance of the DWR and gave bonuses to those jackets that had special features and hydrophobic down.
Fit
To assess for fit, we had numerous people wear each jacket and give their opinions and feedback. We also wore them side-by-side, noticing the differences in fit for each. In particular, we paid special attention to the length of sleeves and hemlines, and whether any constrictions were felt in the shoulders, upper back, and chest, especially when moving the arms to the sides and overhead. We tested each jacket with other layers underneath, as well as under a shell jacket.

Compressibility
To test for compressibility, we stuffed each jacket into its provided stuff sack or pocket (or both) and then compared the size of each. Jackets that packed down the smallest received the highest scores, while jackets that packed down large received lower scores.
Features
Most of our testing of features took place in the field. We first identified what features each jacket possessed and then set about testing each of them. Jackets with highly functional features scored better than jackets with features that didn't work as well. We tended to rate the usefulness of the features rather than the quantity. Jackets that were missing needed features lost points, while jackets that had minimal, but well-executed features may have scored well.