S2 Definition of a Statistic?

Right, I'm pretty up to date with my stats..
The only thing which could trip me up is one of those wordy questions

I've just started a practice paper and the first question I got was

"explain breifly what you understand by...
a) a statistic
b) sampling distribution"

I can't find the right bit in the book, can anyone help me out here, or point me in the right direction?

ta luvs.

Reply 1

jazzyj

a statistic is "a random vaiable consisting of any function of the sample data that involves no other quantities"

a sampling unit is "an individual member of a population"

according to my teacher! xx

Reply 2

Jonny W

kimoni

"explain breifly what you understand by...
a) a statistic
b) sampling distribution"

The examiner might like you to include examples.

(a) A statistic is a function of the observed data. For example, if the observed data is X(1), ..., X(n) then (X(1) + ... + X(n)) / n is a statistic.

(b) The sampling distribution of a statistic T is the probability distribution of T. For example, let X(1), ..., X(n) be independently normal with mean m and variance 1. Let T be the statistic (X(1) + ... + X(n)) / n. The the sampling distribution of T is normal with mean m and variance 1/n.

Reply 3

kikzen

does anyone have the ohter definitions for this waffle?

Reply 4

Leekey

kikzen

does anyone have the ohter definitions for this waffle?

Sampling Distribution - When all possible samples of the population have been taken, the probability distribution formed by the samples is known as the sampling distribution. :smile:

*NB - Was from memory so could be inaccurate*

Reply 5

kimoni

Thanks guys, appreciate it!

Reply 6

midnight

Population - a collection of items

Sampling Frame - a list of items in a population

Census - a complete enumeration of a population

Sample - a selection of items from a poulation

Statistic - a random variable consisting of any function of the sample data that contains no other quantities

Null hypotheis - the working hypothesis, which is assumed to be true.

Alternative hypothesis - the hypothesis that describes the situation if H0 is not true

Test statistic - a statistic used in a hypothesis test

Sampling distribution - the distribution of a statistic

Critical region - the range of values of a test statistic that would lead you to reject Ho

Significance level - used to determine the critical regio. It is the level of probability we are prepare to accept. It is the probability of rejecting H0 assuming H0 is true.

They're all the ones i've got