Dave's ESL Cafe's Student Discussion Forums

[Calm-mind]

What's the difference between statistics and statistic?

Why do you use "a" in the phrase "at a hight of 7,000 meters" while "the" is used in the phrase "the hight of this mountain?" I think ,in the first case, there are mamy hights and 7,000 meters is one of them. Is it correct?
Thank you.

[CP]

1. Statistics is a discipline that uses particular methods (statistical methods) to make statements about data. The statements may be descriptive of the data (and of the population or sample from which the data were obtained) or may be inferential and predictive.

When we take lots of data and reduce them to a few useful numbers, we are using statistics / statistical methods to come up with one statistic or maybe several statistics for descriptive and inferential purposes.

Maybe I get the height and weight of every person at your school or company. Then I add all the heights up and divide by the number of people, yielding the arithmetic mean. That's a statistic that gives the average height of persons measured. I can do the same with the people's weights and find out mean weight. With those two simple numbers, I can inform the school or company of the "typical" student's or worker's size. One statistic will be mean height; the other, mean weight.

I can take the same data and describe the males and females separately -- a good idea since there is usually a size difference favoring one sex or the other, depending upon age. I can get further information, such as the variability of the groups: Are most people close to the average height and weight, or is there a lot of variance? If I'm going to order school or company uniforms or lab coats, for example, I'll need to know these things. These statistics are useful, while the mass of raw data is not very informative or useful at all.

Once I know something about the variance, I can compare the people at the school / business with the people in the country or the world and find out whether they are typical of the whole population or are different in some way. Maybe they are all high school seniors, in which case I presume they are taller but lighter than the average person in the country. I will use statistical tests to come up with at least one statistic that tells me whether I can say (at some level of statistical confidence) that this group really is taller or lighter than the population. When I tell my audience that our senior boys are two inches taller than the average man but 25 pounds lighter, I know I am right, because I have the statistics to back me up.

2. I don't know.
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You live a new life for every new language you speak. -Czech proverb

[Calm-mind]

Wow! Thank you extremely very much. I have read your post many times. I see.