Evidence comparison needs to be warranted. In general, stating the differences between your evidence is not enough to win that comparison, you must warrant why that difference matters for the round. Here are some ways you can do that, with direct comparison to weakly warranted methods of evidence comparison. (One thing to note - all of the good examples take more time than the bad examples, which is a good thing. You shouldn't be spreading blippy, unwarranted arguments but should be developing the ones that matter. If you don't care enough about it to warrant it well, is it really important?)
Using the dates on the evidence is a good way to compare evidence, especially evidence making uniqueness claims. It's poorly done a large proportion of the time.
Too often, teams make unwarranted, unimplicated claims for their postdating claims. Simply stating that your evidence is more recent, or that it was written after the evidence they brought up is insufficient for making it better evidence.
Example: "On their Smith evidence from January that the Houthis are fighting back despite peace agreements, postdate them since Jones from MARCH finds that the Houthis have stopped fighting, drop that argument right there." What's wrong with this response?
First, it's unwarranted. What's changed since March to make the Houthis stop fighting? Unless the extent of your argument is "the Houthis just spontaneously decided they're done," you need to give a real explanation for why they would've decided to shift towards your claim instead. You can make this analysis of the Houthi decision calculus outside a card, it just has to be warranted for why their strategy would've changed. Not only is this necessary for a judge to accept your postdating claim, but it gives the judge a real reason to accept your argument beyond just "it was written later" (you don't even know if the date on the card reflects a different version of events, or if the reporter was just too slow to write about the same situation). Second, it's not implicated. Why does postdating even matter in this context? What does this postdating mean for the round? While in some contexts, such as these uniqueness claims, it may make implicit sense to you, with many judges they won't get that immediately, and need warranting. You need to explain why the different date matters for their argument - the situation they're addressing has changed since their evidence was written - and you need to explain what this means for the argument - their arguments are predicated on that old version of events, but they're now nonunique.
Better example: "On their Smith evidence from January that the Houthis are fighting back despite peace agreements, postdate them because since their evidence was written, the Houthis have seen the damage inflicted by the last time they didn't bargain, which is why Jones from March finds that the Houthis have now stopped fighting. This means their argument about stopping the Houthis has already triggered, if anything you vote neg against a risk of breaking that peace."
People often use metrics about the quality of their studies, like sample size or timeframe, to argue that their own article or study is a better one than their opponent's. That's fine, but in most cases, that difference is not warranted in terms of why those differences matter. Implication is necessary!
Weak study comparison
Why does a "better study" make a difference? Most teams won't tell you. If it's unwarranted, it doesn't matter - the buzzword of "comprehensive study" is not a substitute for a warrant. What factor did the other study not consider that changes the result?
Example: "They read you Wallace saying price controls empirically increased access by 20 percent worldwide. But Johnson 16 finds overall, after implementing price controls, access actually fell by 8 percent. Prefer Johnson, since its sample size includes twice as many countries as Wallace." This would probably pass in a round, but in close ones, it's probably insufficient.
Better study comparison
Why does this even matter? What additional benefit do you get from those other countries included in the study, and more importantly, how exactly does that difference in sample size change the internal warrant between price controls and accessibility. Implicating that requires being much more familiar with your evidence. Which additional countries were included in the study? And more specifically, what about the inclusion of those countries makes your study see factors that your opponent's doesn't? This applies to a lot of study comparison arguments people make. Your evidence has a longer timeframe, why does that matter? Your evidence uses different methodology, what does that change about the results? Remember, your implication to the results has to be a reason to prefer your study to the topic in particular - a study that considers fewer countries might be better if your opponent explains that better. Above all, remember that in tight rounds, the majority of judges won't take surface-level analysis as a reason to prefer your evidence unless your opponents made no analysis in the other direction.
Better example: "They read you Wallace saying price controls empirically increased access by 20 percent worldwide. But Johnson 16 finds overall, after implementing price controls, access actually fell by 8 percent. Prefer Johnson, since its sample size includes more developed nations which have insurance systems that are the true determinants of price, instead of pharmaceutical companies directly selling drugs. That means negating is a better way to increase accessibility, keeping access comparatively higher."
This can be applied to empirical studies, but can be applied to pretty much any evidence. As a side note, it's almost always better to have your evidence be specific to whatever the topic is talking about, regardless of if you use that explicitly in a round. Not only do you prevent your opponent from making their own analysis about specificity, but your arguments are more convincing and easier to win if all your evidence is specific to the topic.
Weak specificity comparison
Specificity is probably a method of evidence comparison where not warranting it enough gets some leeway with judges. Yet when the debate gets tight, and there's actual clash on this level, you need to be solidly warranting why the difference matters. What makes the specific area or country or whatever important? What differentiating factors are there that could explain the different conclusions of your cards?
Example: "Then, they read the Lawrence evidence saying infrastructure projects will be underutilized, not generating economic value. However, prefer Donald 15, who finds in the EU specifically, infrastructure projects will generate economic value."
Better specificity comparison
This would probably pass for most judges, but it's still unwarranted. What's so different about the EU that changes the results of the study? You need to give some warrant for a difference between EU projects and others. This applies to every comparison of specificity that teams read on any topic, whether it's arms sales to Saudi Arabia and not countries in general, the national debt of the US and not other countries, drug prices in the developing world and not the developed one. This is probably the easiest to distinguish, but the warrant needs to be there all the same. Think about the characteristics of a country or area you're arguing for that makes it unique. Maybe Saudi Arabia realizes the US is dependent on their oil, maybe US debt is held primarily by other countries, maybe developing nations lack healthcare systems.
Better example: "Then, they read the Lawrence evidence saying infrastructure projects will be underutilized, not generating economic value. Yet in the EU, massive infrastructure gaps persist with a high demand for transport, so prefer Donald 15, who finds in the EU specifically, infrastructure projects will generate economic value."
Almost every debate will have clash on some level between warrants or evidence read. It's your job, regardless of what your opponent does, to solidly win those debates to swing the important parts of the debate to your side. Here are some direct takeaways for your rounds!
1. Warrants take time but resolve key clash.
All of the better methods will take more time. Simply reading a contradicting piece of evidence and pointing out a difference between the two is insufficient without spending the extra time to explain why it matters. When you invest the time to explain those differences, you're able to go more in-depth on a specific layer of the debate instead of spreading yourself thin over a few different issues. This should also mean you think more about prioritization, i.e. what arguments will really swing the round one way or another, since you won't be able to go super in-depth about every piece of differing evidence, especially later on in the round.
2. Read good evidence in case!
While you should be reading recent, comprehensive, specific evidence in every speech, reading it in case matters the most. You'll be using each case much more than any individual response, and that case should usually be the way you win the round. By reading the best evidence in your case, you avoid teams reading better evidence against you and using these methods to beat parts of your case. Put in the time to make sure your case evidence is top-notch! Additionally, if teams read general evidence against you, when frontlining you can smoothly respond with a warrant then extend the evidence with the warrant as a reason to prefer it, integrating your frontlines and your extensions for a much more cohesive speech.