HDTV 1080p vs 720pYour One-Stop Hub for 1080p and 720p HDTV Information

When you are considering buying an HDTV might be confused about which model to choose. 1080p HDTV is not the same as 720p HDTV and the seller may get you to buy the second because it is cheaper. Both TVs are not the same and their characteristics differ considerably. When you choose a plasma TV HD 1080p resolution gives 2,074,000 pixels per image. This TV brings with it a wonderful experience the perfect combination of quality picture and sound that has gained popularity in the market today.

TV 720p resolution is very economical for those who want high-definition television at reasonable prices. 720 indicates the vertical scanning of 720 lines of resolution and 720p, there are 720 vertical lines and 1280 horizontal lines that give the full resolution television quality 720x 1280. The “P” is present in 720 stands for progressive scan, which shows how lines of resolution are set. The lines of resolution on this TV are updated simultaneously. The traditional TV has lines of resolution, which are intimately linked. The odd lines are refreshed first, followed by even lines. This makes the photographic image in progress.

The 1080p Plasma HDTV using progressive scanning and is considered the full high-definition TV in the market today. At the highest resolution, and is marked to be the best on the market today. The picture quality is very clear and very similar to those in Blu Ray. You can connect the HD 1080p plasma TV to a computer and also serve as a monitor. In this case, you can get a resolution is almost doubled. You’ll also have the advantage of having multiple windows that open on one side. It is an advantage that the HDTV 1080p Plasma HDTV has more than 720p. 720p HDTV is not compatible computer and, if you want to connect your TV to a computer, you should go for plasma 1080p HDTV. It also gives the pleasure to play on your computer as well.

The quality of the image has the same 1080p resolution, which is the same technology 2K digital camera and so it comes as a definition of “Full High” When you buy a HD TV and have the means to ‘go for the best, you should go for plasma 1080p, giving you the best return on your investment. If you are on a small budget, you can go for 720p HDTV, but you miss the advanced features you have in 1080p Plasma HDTV. The age of high definition is now in place and its time to replace the standard TV to HDTV 1080p Plasma TV richer and better.

Lamentably, in the current console generation, Nintendo decided to turn away from the popular strategy of juicing the visual capabilities of its hardware to eye-searing levels. YouTube user renebarahona recently gave us a taste of what HD Wii would have been like by cranking up the visuals of a few titles to 720p using the Dolphin emulator on PC. We’ve got two examples, Super Smash Bros. Brawl and Final Fantasy Crystal Chronicles: My Life as a King, posted after the break (be sure to turn on HD mode).

We’re not advocating the shameless emularceny of Wii titles, though it is interesting to see how these games look with a bit extra graphical endowment. To use a standard rate of exchange, it’s about the visual equivalent of three GameCubes duct-taped together — maybe even three-and-a-half. We’re not quite certain.

lousy economy has retailers eager to romance you with deals on high-definition televisions. If you’re in the market, here are some tips:

Find the right price.
“It definitely pays to shop around. But absolutely set a budget first,” says Alfred Poor, author of the online publication “HDTV Almanac,” available at hdtvprofessor.com.

Think about how much you’re willing to spend and scour newspaper circulars and Web sites for prices and special offers. If you plan to finance, budget payments so you pay off the total before any promotion period ends, to avoid hefty interest charges. Also factor in additional costs, such as a media stand, cables and/or delivery. And check to see whether the seller meets or beats a competitor’s price.

Don’t be afraid to go big.
As you marvel at the HDTVs in the showroom, think about how the perfect screen will look in your living room. Then think bigger. “The general rule of thumb is people typically buy too small,” says Richard Fisher, A/V science director of the Web mag HDTV Magazine (hdtvmagazine.com).

Of course, you want a TV that will fit your viewing area without overwhelming it. Fisher says your viewing distance from TV screen to sofa should be four to five times the television’s height. So if a model you like is 2 feet tall, expect to view it from about 8 to 10 feet away. Take a ruler or measuring tape to the store if it helps.

The big two:
LCD and plasma. LCD (liquid crystal display) and plasma (which is phosphorus based) are your two main HDTV options.

LCD TVs come in various screen sizes, so you should find one that’s right for even the shortest viewing distance. LCDs typically use less energy than plasma TVs and generally weigh less, so they’re easier to mount on walls. LCDs also handle bright rooms better than plasmas thanks to a brighter picture.

LCD traditionally got knocked for not registering true blacks and blurring fast-motion action, but today’s LCDs can better handle those issues. For the best color on an LCD, Fisher says look for one with LED backlighting or WCG (wide color gamut) technology. For better fast motion, he says look for an LCD that offers a 120Hz refresh rate. Expect to pay a bit more for such features.

Plasma TVs typically provide richer colors and contrast than LCDs. They likewise handle fast-motion better than inexpensive LCDs, Fisher says.

Plasma TVs still weigh considerably more than LCD sets, with screen sizes often starting at 42 inches. Plasmas also tend to reflect in brighter rooms, so you might want to consider a plasma TV with an anti-glare screen. Oh, and Fisher says plasma is the most power-hungry display you can buy.

Think about HD content.
A high-definition TV doesn’t magically transform audio and video into HD quality – you need to feed it HD content. Fisher recommends you upgrade to HD channels from your cable or satellite provider. And do ask about HD-capable DVRs so you can record HD programming.

Poor also suggests you avoid DVD players that “upconvert” standard DVDs to near-HD quality. He notes the technology built into a quality HDTV should do that job on its own.

What to know about HDMI.
High-Definition Multimedia Interface or HDMI gives you high-def audio and video via a single cable. To accommodate HDMI-friendly devices, make sure the HDTV you purchase has two or more HDMI slots.

HDMI cables in stores can be expensive, often starting at $30 and exceeding $100. Poor says skip those pricey cables and instead buy the cheapest HDMI cable you can find on the Internet. That way you’re only looking at $10 to $15 for a 3- to 6-foot cable. “If it works, you’re done,” Poor says.

Fisher also suggests you skip the pricey HDMI cables, but only if you’re connecting devices close to your HDTV. If you plan to run HDMI cable more than 10 feet, Fisher says, you’re probably better off with the pricier stuff. Whatever cable you buy, Fisher says make sure it’s HDMI 1.3 certified.

Panasonic Corporation of North America (NYSE: PC) , the industry leader in high definition Plasma and LCD televisions, introduced its expanded line of VIERA HDTVs at the 2009 Consumer Electronics Show. Building upon its award winning portfolio of high definition televisions, Panasonic will broaden its offering in 2009 by introducing new screen sizes in both Plasma and LCD lines with a new 54-inch class plasma and 19-inch class LCD. In addition, VIERA will extend its unique technology features, such as the acclaimed VIERA CAST(R) web menu, to additional model lines.

VIERA CAST, originally launched in 2008, will broaden its entertainment offering with the addition of Amazon’s VOD streaming video service. Panasonic also extended the prestigious THX(R) Certified Display to three product lines. With a continuing emphasis on improving the television’s performance and reducing the impact on the planet’s carbon footprint, Panasonic’s 2009 line of VIERA HDTVs have improved their energy efficiency vs. last year’s models, while also improving the overall picture performance of the HDTVs.

Year after year, Panasonic has been dedicated to bringing new picture improving technologies to HDTVs and 2009′s line-up continues that trend. With the digital transition on the horizon and an increased awareness among consumers of high definition, consumers now demand blacker blacks, faster response times and the billions of colors that Panasonic VIERA HDTVs deliver.

In 2008, Panasonic offered one VIERA HDTV series that had innovative internet enabled VIERA CAST feature. In 2009, it will be extended to three series – The Z1 series, the V10 series and the G10 series. In addition to the continuation of such favorite entertainment sites as Google’s YouTube(TM), Picasa(TM) Web Album, Bloomberg and weather service; a consumer will now have an access to HD movie rental via Amazon Video-on-Demand. Panasonic has also improved VIERA CAST interface by implementing quick keyword input (like a cell phone) to help retrieve favorite content faster and easier. Panasonic HDTVs VIERA Link – a technology that utilizes HDMI-CEC (Consumer Electronics Control) and allows a consumer to operate all VIERA Link(TM) compatible A/V components using only the TV’s remote control and helpful on-screen menus. In addition to operating a VIERA HDTV, video source (Blu-ray and DVD player) and home theater receiver; VIERA Link permits operation of a network camera, ideal for monitoring of a home/nursery*. A VIERA Link capable Network Camera BL-C210A can be connected to a VIERA HDTV and controlled via VIERA Link remote. Users can then watch their child, pet and/or property by installing the camera and networking to the VIERA HDTV via Ethernet cable. The BL-C210A will be available in the United States in the summer of 2009.

As in 2008, all Panasonic VIERA HDTVs feature VIERA Image Viewer(TM) a function for easy viewing of digital still photos and in some models, the ability to play back AVCHD video recorded on SD card.

For 2009, VIERA Plasma HDTVs are rated, as in 2008, to have a lifespan of 100,000 hours. This is more than 30 years of viewing when watched for 8 hours a day, before the TV reaches half brightness. To further improve picture quality, VIERA HDTVs feature some breakthrough consumer innovations like 600Hz Sub-field Drive and Infinite Black panel with improved contrast ratios. In 2008, Panasonic offered VIERA HDTV models that were THX certified and in 2009, the prestigious certification will be extended to 8 VIERA models (The V10 series and the G10 series). THX Ltd. works closely with Panasonic from initial product design phase to the final product rollout in the market. THX certification ensures that each display can present all HD and standard definition content to the maximum resolution with accurate color and luminance levels.

Panasonic’s commitment to improving the environment was confirmed this year as all of its 2009 VIERA HDTVs qualified for Energy Star certification. As in the past, VIERA Plasma HDTVs are lead and mercury free.

“Panasonic’s superior quality, connectivity and service continues to distinguish the VIERA line,” said Bob Perry, Executive Vice President, Panasonic Consumer Electronics Company. “Not only have our VIERA HDTVs received critical acclaim from consumer and trade publications, but Panasonic has maintained the market lead for the majority of the last three years. Panasonic has never rested on its laurels and the 2009 VIERA line continues that thinking. This year Panasonic has created the ‘Neo-PDP’ line with a brighter panel, double luminance efficiency, deeper blacks with improved contrast ratio and 1080 TV lines of Moving Picture Resolution. Our corporate philosophy of Ideas for Life is borne out by our attention to the consumer- to provide the ultimate entertainment experience in an easy to use format. That is why we have expanded our VIERA CAST feature and continued to improve the functionality of VIERA Link.”

The 1080p vs 720p, or 720p vs 1080p, resolution decision [(1,920 x 1,080 pixels) vs (1,280 x 720)] should be made with an appreciation that resolution is not the only factor contributing to picture quality. In fact, resolution comes fourth in a recent SMPTE (Society of Motion Pictures and Television Engineers) study which ranked contrast ratio, color saturation, color temperature or greyscale ahead of it in ranking picture aspects the human eye sees in order of importance.

Two factors influence which resolution is more appropriate namely,

Screen size and Viewing distance.

In general terms, the closer you sit to the on-screen image the more detail you can see as the image fills more of your field of vision. So the closer you are getting to the display/screen the higher the resolution should be getting to maintain picture quality. Moving away from the display/screen reduces the discernible difference between resolutions eg. 1080p vs 720p.

Below is a table matching up various screen sizes with the optimum viewing distances for 720p or 1080p resolutions.

Screen Size

(diagonal) 1080p Resolution

optimum viewing distance 720p Resolution

optimum viewing distance

32 inches 50.21(4.2 feet, 1.3m) 75.31(6.3 feet, 1.9m)

42 inches 65.89 inches (5.5 feet, 1.7m) 98.83 (8.2 feet, 2.5m)

58 inches 91.01inches (7.6 feet, 2.3m) 136.51(11.4 feet, 3.4m)

100 inches 156.9inches(13.0 feet,4.0m) 235.34(19.6 feet, 6.0m)

120 inches 188.26 inches (15.7 feet, 4.8m) 282.35(23.5 feet, 7.2m)

A chart of optimal viewing distances in one inch increments is available from HDGuru.

1080p vs 720p Choice for Front Projectors

From the table above it can be seen that the optimum viewing distance for common projected images sizes (100 and 120 inch diagonal) the optimum viewing distance is going to be outside the home theater room. In fact, you even need a large home theater to sit at the optimum viewing distance for 1080p – there is a case for even higher resolutions to be available. So for optimum viewing, you need to purchase a 1080 resolution projector and sit a good distance from the screen.

Keep in mind though that if you choose 720p and are not sitting at the optimum recommended distance then the picture quality is only going to be slightly reduced not vastly reduced. Both 1080p and 720p can deliver excellent picture quality.

1080p vs 720p Choice for HDTV

While you could consider what consider what video sources you might have available (eg. Sony Playstation 3 and Xbox 360 have 1080p games) or the advantage of selecting 1080p to future proof your situation, for determining if 1080p will have any visual advantage over 720p have a look at the following simple chart from Carlton Bale. The chart shows how close you need to sit to be able to detect the benefits of a higher resolution screen. For an answer see where your likely seating distance will fall given your television room layout.

Another factor which will influence a choice between 1080p and 720p for a HDTV is the generally limited range of features in comparison to 1080p models.

The question I am most frequently asked about this resolution comparison is, “Should I get 1080p resolution in my LCD Television?” There are a few obvious questions I ask in response:

What size is the TV?

Are you using it for professional editing?

Do you have a Sony Playstation 3 or XBox 360 for gaming (both consoles have 1080p games and the PS3 is also a Blu Ray player)?

Do you have a Sony Blu Ray DVD player?

Generally, the answer to the above questions is, “no” and the answer to whether or not the consumer should get a 1080p display is usually no as well. It’s just not worth the extra $$. Here’s why:

The 1080p question is really the result of a technology battle between LCD and Plasma. Higher resolutions are easier for LCD manufacturers to produce, and more cost effective. It’s a specification bragging battle as in, “we’ve got the 1080p resolution and you don’t.” Now that plasma manufacturers have caught up let’s analyze what is does for you the consumer.

Unless you are into video editing, or extreme graphic computer use, 1080p does hardly anything at all except hit you in the pocket book! It took years of pressure for broadcasters to finally produce 1080i or 720p and there are NO plans to pump out 1080p on cable, satellite, or broadcast. There is ONE DVD format that puts out a 1080p signal and that is Blu Ray. Blu Ray, is a great DVD technology and the picture quality is awesome, however it’s no better than 1080i or 720p in my opinion. I base this opinion on some pretty thorough testing. Recently, our staff reviewed a 65″ Panasonic 1080p plasma, a 52″ Sharp 1080p LCD and a Sony 46″ 1080p LCD TV. We viewed several movies via the Sony Blu Ray player which conveniently has a resolution toggle button on the remote control. In order to perform a fair test of 1080i vs. 1080p we sent participants out of the room after having shown them the DVDs with both resolutions several times. Then we called them back in with one of the resolutions displaying and asked them whether it was the 1080p or 1080i signal. We repeated this process 10 times and, guess what? They had no clue and could not differentiate at all between the two. This feedback came from a team who knows TVs. In fact they seemed to favor the 1080i signal slightly (60/40). It’s incredibly difficult to see the difference even in a side by side test.

So why make it? Why produce 1080p? So you’ll pony up and buy it crazy!! Spend more money! Open up that billfold! The manufacturers need to produce products that will sell for more in an environment of ever falling TV prices. That, and the aforementioned LCD vs. Plasma battle.

So what to buy? Find yourself a nice 1366 X 768 TV produced by a Tier 1 manufacturer and let it go at that. Put the $1000 you will save into a good set of speakers and receiver for your home theater. A 1080p display does not look any better than a 720p (1080i) TV when viewing 1) A High Definition signal via cable, satellite or broadcast 2) a DVD signal 3) And the biggest question of all, “Does it even look better with the limited Blu Ray content available?” 4) A lowly non-HD cable or satellite signal may view better on the lower resolution 1080i (720p) LCD TV due to the fact that a 1080p display will have to perform some extreme up conversion to get to its native resolution.

Are there any differences between the two technologies?

When it comes to flat screen TVs the two technologies LCD and Plasma seem very alike with almost lifelike images and the ability to be hung on the wall. Although LCD tvs and Plasma tvs displays may look very similar in the shops, there are various differences between the two technologies.

How LCD tvs work

LCD is an abbreviation for Liquid Crystal Display. A LCD tv screen is made up of two clear panels between which is a matrix of colour liquid filled pixels. These pixels respond to a small voltage which makes them change state by twisting or untwisting which allows light to pass through them or to be blocked depending on the state of the pixel. This process of twisting takes very little power. The pixels are either red, green or blue and they are structured in a matrix of millions of pixels to make a picture. The coloured pixels of the panel are illuminated from Behind with a back light to show their colour, and areas of light and dark, depending on how the pixels are twisted. Lcd screens are available in small sizes for watches up to 108 inches for large televisions. Manufacturers such as LG, Samsung, Hitachi, Panasonic, JVC, Pioneer, Sharp, Toshiba, Philips and Sony have a range of lcd televisions available.

How plasma tvs works

A Plasma tv screen comprises of millions of tiny ‘light bulbs’ which are tiny glass cells filled with inert gases such as xenon and neon. These cells are illuminated by a current being applied to electrodes in the gas filled cell and its atoms become ‘excited’ to a plasma and emit photons of ultraviolet light. These photons in turn strike a phosphor coating which emits visible light. The colour of the visible light emitted by each cell depends on the three different coloured phosphors – green, blue and red, and can together make billions of colours when combined. As with the LCD tv screen, the millions of cells combine to form the image on the screen. Currently the only manufacturers of Plasma tvs in the UK are Panasonic, Pioneer, Philips, LG, and Samsung. Plasma tvs are available in sizes from 32 inches to 150 inches.

A comparison of the Picture quality and Performance

The Brightness of the picture

The picture on LCD tv screens can be brighter than Plasma tvs. Depending on where the television is located and what is being viewed will determine how this difference in screen brightness is perceived. However both Plasma tv and LCD tv screens are capable of producing brightness levels that in normal viewing conditions are in excess of what is needed.

Black Levels and the Contrast Ratio

This is a measure of the difference of the luminosity of the brightest white on the screen and the darkest black. So a contrast ratio of 3000:1 means that the brightest white is 3000x brighter than the darkest black. Details can be more easily differentiated the higher the contrast ratio is as long as the the black levels aren’t ‘grey’. Previous models of LCD tvs had lower contrast ratio than plasma tvs because the pixels weren’t able to block the back light for dark areas and the light would leak through making the image lighter. Improvements in technology have reduced this leakage so that the contrast ratio is much closer to those of plama tvs. But ultimately plasmas are able to produce blacker blacks because the pixel cells are able to be switched off instead of blocking the light as lcd tvs do. The blacker the black on a tv the better the picture quality it is able to produce. The colour saturation or colour palette is affected if the blacks aren’t black enough . When the black level on a plasma is compared with the black level on an comparable priced LCD tv, the plasma tv black often makes the LCD tv black look grey.

Colour Saturation

colour saturation is a measure, in the presence of grey shades, of colour purity or how accurate the colours are on the screen. The higher the colour saturation the more accurate the colour rendition. With blacks that aren’t as black the grey shades will be higher resulting in a lower colour saturation. Plasma offer better levels of colour saturation due to better black levels because of their ability to switch of pixels that aren’t in use, preventing diffusion of colours by stray light emissions. This results in hues and tints that are more life like colourful.

Colour Gamut

The colour gamut is the set of possible coulors within a colour spectrum that a screen can display. The top end models of Plasma tv and LCD tv manufacturers are claiming that the colour gamut is near to the full spectrum. On comparable priced LCD tv and Plasma tvs, the Plasma tv again out performs the LCD tv on all but the top end models. The reason for this is that for the same manufacturers the colour gamut isnt as good on the lower models. On plasma tv models the cheaper models don’t have such a difference compared to more expensive models from the same manufacturer.

TV Screen Resolution

The screen resolution is a measure of the total pixels that makes the screen. The higher the definition, the higher the resolution and greater the detail and sharpness will be in the picture. LCD HDTVs have a resolution 1920 pixels x 1080 pixels or 1080P are, size for size, at a lower price than comparable Plasma tvs. 1080 is the vertical reolution and the P is for progressive scan because it isn’t interlaced. The best Plasma tv and LCD tvs screens above 37 inches are HDTVs with the same 1080P resolution i.e. there is no difference. At sizes of 37 inches down to 32 inches the best LCD tv screens are still 1080P set but the Plasma tvs are lower resolution HD ready 720P (1280 pixels x720 pixels) models. There aren’t any Plasma tvs smaller than 32 inches, but there are many LCD tv models.

Response Time and Refresh Rate

How a screen is able to deal with fast moving pictures without blurring is a combination of the refresh rate and the response times. The response time is a measure of the speed of a screen to quickly change when an input signal is received. Early LCD tvs had a lot of motion blur caused by slow response times because the pixels took too long to change from on to on to off, and back on to on to refresh the image. Improvements in screen technology has improved this response time to the point where it is no longer the cause of the motion blur. Now the cause is mainly the refresh rate or frame rate.

Less expensive models of Plasma televisions and LCD televisions operate at frame rates of 50 frames per second or 50hz. Recently 100hz tv models were launched on more expensive models which reduced motion blur by creating an extra middle frame which is placed in between the normal frames. This middle frame is created by advanced signal processing software that interpolates what the middle frame would look like. The addition of the middle frame results in moving images that are fluid with little, if any definition loss. Even with 100hz the best plasma tvs still out perform the best LCD tv models but by a narrowing margin because of reduced response times and 100hz and 200hz.

The Viewing Angle

This is the maximum side angle that a viewer can see the image on the screen clearly. Plasma tvs usually have a viewing angle of between 160 degrees to 180 degrees whereas LCD tvs have a viewing angle of around 100 degrees after which the picture dulls.

The screen surface

LCD tv screens are available with matt finish screens which reduce glare whereas Plasma tvs have a reflective screen.

Image Burn-in

For Plasma tvs With prolonged displaying of non-moving images, graphics or text, such as a menu bar, channel logo, or news scroll a permanent ghost image can be permanently burned on the screen with a darkened appearance. SO even if the image on the screen is changed or removed it can’t be removed for the rest of the plasma tvs life and is always seen as a shadow image. Regardless of how long a static image is displayed on an LCD tv they aren’t affected by burn-in. But the problem of burn-in is exaggerated and unlikely under normal viewing.

Image retention

image retention is often confused with burn-in which has similar characteristics. However image retention is a ‘ghost image’ that appears on a plasma tvs after a still picture has been displayed for an extended period of time, but then disappears when a bright new image is displayed. Or it vanishes after a few seconds. By having a ‘break in’ period of about 100 hours from new, this can be minimised. Whist watching programs during this break in period care should be taken to watch programs that don’t have any static bright images like station logos and scrolling news headlines at the bottom of the screen. Also try to watch programs that fill the whole of the screen. It recommended that during this period the brightness and the contrast is kept at about a mid level. These characteristics of image retention and burn-in have been greatly reduced by technical improvements to reduce the possibility of burn-in or image retention.

Power consumption

The power consumption of an LCD tv is virtually constant because they have a back light that is on all of the time. The back light can be manually adjusted but uses less power on a low setting and more power on a high setting. The modulation of the LCD tvs screen pixels takes very little power.

On a plasma tv the gas is charged in each of the pixels to emit light. When more light is in a scene the plasma tv uses more energy. When the brightness is high the plasma tv use more energy and when the brightness is low the plasma tv uses less energy. So the power consumption will vary depending on what is being displayed.

On paper it might appear that the Plasma tvs employ a lot more power than LCD tvs. Plasma tv manufacturers have a tendency to quote the most power usage at full brightness. But the plasma tvs power power consumption varies depending on the signal and the amount dark and bright areas on the screen. Studies have shown that when watching predominantly dark programs and movies the average power power consumption of an identical sized plasma tv is really lower than LCD tv. However if lots of cartoons and sport are watched then the LCD tv consumes less power. Accordingly on average with varied viewing content there is little difference between LCD tvs and Plasma tvs. Plasma tv manufacturers are shortly going to be launching models that will lessen the power consumption by over half.

Plasma tv Life expectancy

Many ‘experts’ claim that plasma tvs don’t last very long. But in reality manufactures are publishing life expectancy figures of 100000 hours, this equates to 11.5 years of non stop use. Clearly there is no reason for concern.

Conclusion – which should you buy?

Both technologies have advantages. Plasmas tvs generally have a superior subjective picture with healthier black level, higher contrast, and better colour rendering than LCD TVs. Although LCD TVs have higher brightness, and no screen burn-in worries, and are lighter and thinner. This is not always the case becausea good LCD TV could have a better picture than an average or poor plasma TV. Although on balance I think that a plasma tv is the better option with added advantages. Ultimately you get what you pay for so spend as much as you can manage to pay for on you preferred format.

AVS Forum is THE forum for all audio/video fans in the world. Here is the link to their official thread on the 1080p vs 720p discussion.