1. Dec 14, 2004

### sotellme

what does it mean when it says; " height*width at half height " ?

so far i just know that height multiply with width but what does it mean with " at half height" ??? :yuck:

does anyone know what kind of formula is this?

thanks!

2. Dec 14, 2004

### cyby

If width is at half the height, that means the thing is twice as long as it is wide....

3. Dec 14, 2004

### cyby

What is the context of this question?

4. Dec 14, 2004

### sotellme

about gas chromatography...but this is a math question.

instead of writing it in words can you express it in numbers, because i still don't get what you mean with words

thanks!

5. Dec 14, 2004

### cyby

Well, can I look at the question verbatim please?

6. Dec 14, 2004

### Tide

Look at the graph and determine where its maximum is. The y-value at that point (ordinate) is referred to the "height." If the spectrum (distribution) is monotonically decreasing from its maximum value then you can find two unique locations where the value of the distribution is half its maximum value. The difference in x-values (abscissas) between those points is referred to as the "width at half maximum."

7. Dec 15, 2004

### rdt2

Think of a curve such as a normal distribution. The peak is the height. You can also measure the width of the curve at half of this height. Multiplying height*(width at half height) would give you some measure of the sharpness of the peak.

8. Dec 15, 2004

### Tide

Not really. In fact, for a normal distribution, the product of width and height is a measure of the area under the curve which is 1. The area, in this case is the total probability and it makes no difference how sharply peaked the curve is.

9. Dec 15, 2004

thanks all!