An investigation by Business Insider found that, "United had more pet deaths in 2016 than any other major US airline." Given United's recent public relations debacle, is this true, too? Technically yes, but statistically no. Becasue it's the statistics that matter, not the raw numbers.
Difference in difference is a statistical technique used in observational studies. It can provide insight – but don't be fooled by numbers and p-values into believing it is necessarily true. 
Statistics is difficult, and choosing the proper tools becomes more challenging as experiments become more complex. That's why it's not uncommon for large genetics or epidemiological studies to have a biostatistician as a co-author. Perhaps more biomedical studies should follow suit.
There are a lot of Seattle Seahawks haters out there. Apparently, a popular insult hurled at the NFL team is that it is a "Johnny-come-lately" franchise supported by a bunch of fair-weather fans, now that the team is good. The problem for the haters, however, is that statistics show it's not true.
Anyone remotely familiar with the scientific method understands that just like a ruler or a telescope, statistics is a tool. Scientists use the tool primarily for one purpose: To answer the question, "Is my data meaningful?" Properly used, statistics is one of science's most powerful tools. But used improperly, statistics can be highly misleading.
Nate Silver, statistician and election forecaster, told ABC News that election forecasts that gave Hillary Clinton a 99% of chance of winning didn't "pass a common sense test." That is certainly true. What he left unsaid -- possibly because it wouldn't be good for his career -- is that all election forecasts that provide a "chance of winning" don't pass the science test.
What is a scientific poll? First, it is a misnomer. There is nothing scientific about a poll. Second, it is conducted using sound statistical techniques. What's more, savvy politicos know that not just any poll will do.