How do sample population studies equate to accurate statistics?

If it's a sample but not the whole population that's being studied/surveyed/polled, then the truth will never be known. How can a sample tell us about the entire planet?

How do sample population studies equate to accurate statistics?
They can't and don't. You're right statistics are not very dependable... you know that old saying numbers don't lie? But in reality they can, and they do. It's easy to manipulate numbers to get them to say what you want. Example the ratio toothpaste commercials use 2 out of 3 dentists recommend this. But if you put that ratio on a scale of millions it would be like 1 million dentist do not recommend this brand... and I'm not sure if that's a number I'm comfortable with. And percentages vs. fractions: Percentages always sound better because the numbers are generally smaller. Example, why say 1.4 million people in North America has aids, when it sounds less horrifying just to say 0.8%? And those numbers are completely true... But I hope you get what I'm saying. And people use numbers from biased sites. If one person gets a set of statistics from one site to 'prove' something another can get a set to ‘prove’ the exact opposite. And it is simply impossible to get an accurate reason for a whole population from just surveying a fraction of the people. That's how we get numbers that prove both sides of an argument absolutely right... and that's bad.
Reply:a sample population isnt meant to tell you about the entire plannet, its meant to tell you about a particular community about a particular subject. Like, if there are 1000 english professors in a department, you are not going to be able to question all of them, you take a sample of say 250 and ask them a question about what they teach in english class, and you get to see a window of what the rest might teach.