March 16, 2009 7:50 AM PDT

Introducing series reviews of HDTVs

What's the difference between the 42-, 46-, and 50-inch version of the 'same' TV? Not much.

(Credit: Panasonic)

As you may have noticed, I've recently changed the way I do reviews of HDTVs at CNET. I call the change "series reviews," and I'm curious to know what you think. But first I'll tell you why I did it.

Individual HDTVs are typically members of a series, where the only difference on the specification sheet between various models in a manufacturer's lineup is screen size. A great example is the Panasonic TC-PS1 series, which includes six screen sizes at various price points, from 42 to 65 inches. In my review of the TC-PS1 series, I only performed a hands-on evaluation of the 42-inch model. But I also posted the review to the 46-inch and the 50-inch model, making sure to explain that I didn't actually perform hands-on evaluations of them.

Previously, we would review one screen size in a series and post a simple note (example), not a review, on the other screen sizes, basically saying that you could expect similar picture quality from all screen sizes in the series.

Why the change?

1. I simply can't perform hands-on evaluations of every screen size in a series. At best I can review one, or at most two sizes in a particular series. It's also less-constructive, given limited time and resources, to review more than one screen size in a series at the expense of reviewing other HDTVs.

2. Given my experience reviewing HDTVs, I generally do expect models in the same series, which share identical specs, to have similar picture quality regardless of size. Examples of series in which I've reviewed more than one model include nearly-identical LG PG60 series (I reviewed the 50- and the 60-inch models), the Sony KDL-XBR2 series (40-, 46-, and 52-inch models), the Panasonic TH-PZ800U series (50- and 58-inch), and the Panasonic TH-PX77U series (42- and 50-inch). The latter two did evince some differences in black-level performance from one model to the next, but overall picture quality was still very similar. That said, my application of the series concept won't be universal--in the Panasonic TC-PS1 series, for example, I'm not applying the review to the largest three models in the series, because I reviewed the smallest. When series span a large gamut of sizes, I'll judge which ones get the review on a case-by-case basis.

3. Many CNET readers use the Best HDTVs and All HDTV reviews lists to find and compare products. These lists point only to reviewed products, so unreviewed screen sizes in a series wouldn't appear on the lists, despite being perfectly viable choices. Applying a review to other screen sizes in a series makes it easier for shoppers to find the product since it allows that product to appear on the lists, which can be sorted by screen size.

4. Unfortunately, I depend on manufacturers to send review samples. Often, the manufacturer will not have the screen size I ask for, which leaves me with a tough choice: take the size offered and review it, or wait until the size I ask for becomes available. In most cases, to ensure a timely review, I'll opt for the former choice, which means that a potentially desirable screen size (such as the 46-inch and 50-inch members of the Panasonic TC-P50S1 series) would have gone unreviewed, at least until the manufacturer comes through.

On the flip side is the very legitimate protest that sounds something like: "Hey Katzmaier, it's totally misleading to post a hands-on review of a product you didn't actually touch."

That's why I make it clear that hands-on evaluations only took place on one size, and that picture quality may vary somewhat on other sizes.

For that matter, it's important to remember that performance can vary between different samples of the exact same product. My hands-on review is technically only valid for the exact TC-P42S1 I reviewed, not any of the other TC-P42S1's out there. CNET's user opinions are rife with examples of people who experience issues I didn't during my review, or people whose HDTVs don't exhibit issues I complain about. Many of those differences are due to variations between my review sample and the user's product.

Series reviews aren't perfect, I know. In a perfect world I'd be able to review every product hands-on with direct comparisons to the competition. Ideally, I'd test multiple samples of the same product to establish an average baseline, and integrate the experiences of users and other reviewers into the perfect review. That would rock. But it's not gonna happen.

In my opinion, series reviews are a good solution to the problems outlined above. They allow more readers to gain the benefit of the review, and further stress the important point that screen size is not a major factor in picture quality. Hopefully, this approach will lead to people finding the reviews more easily, and thus making more-informed buying decisions.

What do you think? Are series reviews of HDTVs a good idea, or does it just lead to more reader confusion? Let me know in comments.