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The science mechanics were changed considerable with Version 0.23. Each experiment still has a fixed pool of science-points (per situation) which can be obtained from it, but only a fraction of this pool can be obtained through transmission. When you want more, you must return the experiment results.

When you don't transmit, you can still recover all the science-points through recovery alone. Most experiments will return 100% of the pool by recovery. Only a few experiments, like the materials lab or the mytery goo, leave some science points behind after a recovery, so you can squeeze out some more points with a second recovery. Unfortunately a recovery depletes those points which can be transmitted first, which means that after you returned them once, transmitting is pointless.

On the other hand, transmitting and then returning can bring you some extra points. But those two experiments where this makes sense - the material science and the goo experiment - can not be reused after transmitting which makes this moot. Or rather would make it moot, when there wouldn't be the new science lab module part, which allows you to reset them in the field. The science module also allows you to further analyze experiments before transmitting which increases the part of the pool which can be exploited through transmission. Tthe ideal way to gain the most science out of these parts in one mission is now:

1. perform them
2. analyze them with the science lab
3. transmit them
4. reset them with the science lab
5. perform them again
6. return them

Alternatively you can also carry two of them (per situation) and recover them both. This will also give you all the points you can get.

Currently, you are able to gain ~125% of the initial value of the given science. Each time you perform science, you reduce the value you will receive in the future. Regardless of how you acquire it, you will always end up maxing out at ~125% the initial value for a particular area and method of doing science. It doesn't matter if you transmit your science or return it to Kerbin. The actual maximum is dependant on the type of science, and varies between 110% and 180% of the initial value.

Also, note that I mentioned the area that science is performed. There's a difference between the surface of Kerbin, the upper atmosphere of Kerbin, and the orbit of the Mun, and each of the places, along with others have their own maximums of science that can be performed. Also note that the science you get from these different areas can be scaled differently. The KSP wiki article on science explains all of these parameters (or in some cases, at least tries to) much better than I could in this limited space.

Now, there is good reason for choosing transmission over return, or vice versa. Early in the career, you don't have access to RTG's, solar panels, or even batteries. This makes transmitting science impractical at best, as you need electricity from your engines in order to transmit again, so you need to return your science. Conversely, if you're sending a robotic mission to Jool, it's impractical return a dozen Science Jr. pods and Mystery Goo containers if you want to gather science from as many of the moons as possible. You're better off sticking a bunch of solar panels on it and transmitting often. As of the 0.23 update, you also have to weigh the effect of the transmission cap on science: you'll only ever get 40% of the maximum science from transmission alone; and without a lab attached, some of the experiments are single use only. Sooner or later, you'll need to return the samples.

Basically, if the cost (in terms of electricity) isn't too high to transmit and you're able to reacquire the same science easily, transmit it, but always hold on to the last bit of science you have if you're returning the craft to Kerbin.
Basically, prefer return over transmission due to transmission cap and single use experiments, but always include the possibility of transmission.

Currently, you are able to gain ~125% of the initial value of the given science. Each time you perform science, you reduce the value you will receive in the future. Regardless of how you acquire it, you will always end up maxing out at ~125% the initial value for a particular area and method of doing science. It doesn't matter if you transmit your science or return it to Kerbin. The actual maximum is dependant on the type of science, and varies between 110% and 180% of the initial value.

Also, note that I mentioned the area that science is performed. There's a difference between the surface of Kerbin, the upper atmosphere of Kerbin, and the orbit of the Mun, and each of the places, along with others have their own maximums of science that can be performed. Also note that the science you get from these different areas can be scaled differently. The KSP wiki article on science explains all of these parameters (or in some cases, at least tries to) much better than I could in this limited space.

Now, there is good reason for choosing transmission over return, or vice versa. Early in the career, you don't have access to RTG's, solar panels, or even batteries. This makes transmitting science impractical at best, as you need electricity from your engines in order to transmit again, so you need to return your science. Conversely, if you're sending a robotic mission to Jool, it's impractical return a dozen Science Jr. pods and Mystery Goo containers if you want to gather science from as many of the moons as possible. You're better off sticking a bunch of solar panels on it and transmitting often. As of the 0.23 update, you also have to weigh the effect of the transmission cap on science: you'll only ever get 40% of the maximum science from transmission alone; and without a lab attached, some of the experiments are single use only. Sooner or later, you'll need to return the samples.

Basically, if the cost (in terms of electricity) isn't too high to transmit and you're able to reacquire the same science easily, transmit it, but always hold on to the last bit of science you have if you're returning the craft to Kerbin.
Basically, prefer return over transmission due to transmission cap and single use experiments, but always include the possibility of transmission.

The science mechanics were changed considerable with Version 0.23. Each experiment still has a fixed pool of science-points (per situation) which can be obtained from it, but only a fraction of this pool can be obtained through transmission. When you want more, you must return the experiment results.

When you don't transmit, you can still recover all the science-points through recovery alone. Most experiments will return 100% of the pool by recovery. Only a few experiments, like the materials lab or the mytery goo, leave some science points behind after a recovery, so you can squeeze out some more points with a second recovery. Unfortunately a recovery depletes those points which can be transmitted first, which means that after you returned them once, transmitting is pointless.

On the other hand, transmitting and then returning can bring you some extra points. But those two experiments where this makes sense - the material science and the goo experiment - can not be reused after transmitting which makes this moot. Or rather would make it moot, when there wouldn't be the new science lab module part, which allows you to reset them in the field. The science module also allows you to further analyze experiments before transmitting which increases the part of the pool which can be exploited through transmission. Tthe ideal way to gain the most science out of these parts in one mission is now:

1. perform them
2. analyze them with the science lab
3. transmit them
4. reset them with the science lab
5. perform them again
6. return them

Alternatively you can also carry two of them (per situation) and recover them both. This will also give you all the points you can get.

Currently, you are able to gain ~125% of the initial value of the given science. Each time you perform science, you reduce the value you will receive in the future. Regardless of how you acquire it, you will always end up maxing out at ~125% the initial value for a particular area and method of doing science. It doesn't matter if you transmit your science or return it to Kerbin. The actual maximum is dependant on the type of science, and varies between 110% and 180% of the initial value.

Also, note that I mentioned the area that science is performed. There's a difference between the surface of Kerbin, the upper atmosphere of Kerbin, and the orbit of the Mun, and each of the places, along with others have their own maximums of science that can be performed. Also note that the science you get from these different areas can be scaled differently. The KSP wiki article on science explains all of these parameters (or in some cases, at least tries to) much better than I could in this limited space.

Now, there is good reason for choosing transmission over return, or vice versa. Early in the career, you don't have access to RTG's, solar panels, or even batteries. This makes transmitting science impractical at best, as you need electricity from your engines in order to transmit again, so you need to return your science. Conversely, if you're sending a robotic mission to Jool, it's impractical return a dozen Science Jr. pods and Mystery Goo containers if you want to gather science from as many of the moons as possible. You're better off sticking a bunch of solar panels on it and transmitting often.

Basically, if the cost (in terms of electricity) isn't too high to transmit and you're able to reacquire the same science easily, transmit it, but always hold on to the last bit of science you have if you're returning the craft to Kerbin.

Currently, you are able to gain ~125% of the initial value of the given science. Each time you perform science, you reduce the value you will receive in the future. Regardless of how you acquire it, you will always end up maxing out at ~125% the initial value for a particular area and method of doing science. It doesn't matter if you transmit your science or return it to Kerbin. The actual maximum is dependant on the type of science, and varies between 110% and 180% of the initial value.

Also, note that I mentioned the area that science is performed. There's a difference between the surface of Kerbin, the upper atmosphere of Kerbin, and the orbit of the Mun, and each of the places, along with others have their own maximums of science that can be performed. Also note that the science you get from these different areas can be scaled differently. The KSP wiki article on science explains all of these parameters (or in some cases, at least tries to) much better than I could in this limited space.

Now, there is good reason for choosing transmission over return, or vice versa. Early in the career, you don't have access to RTG's, solar panels, or even batteries. This makes transmitting science impractical at best, as you need electricity from your engines in order to transmit again, so you need to return your science. Conversely, if you're sending a robotic mission to Jool, it's impractical return a dozen Science Jr. pods and Mystery Goo containers if you want to gather science from as many of the moons as possible. You're better off sticking a bunch of solar panels on it and transmitting often. As of the 0.23 update, you also have to weigh the effect of the transmission cap on science: you'll only ever get 40% of the maximum science from transmission alone; and without a lab attached, some of the experiments are single use only. Sooner or later, you'll need to return the samples.

Basically, if the cost (in terms of electricity) isn't too high to transmit and you're able to reacquire the same science easily, transmit it, but always hold on to the last bit of science you have if you're returning the craft to Kerbin.
Basically, prefer return over transmission due to transmission cap and single use experiments, but always include the possibility of transmission.