Addenda B

Some Concepts and Properties of Integral and Statistical Inference

B.1. Some Properties of Integral

B.1.1. Functions of Bounded Variation

Definition B.1.1

image is a finite function on image. Points of division on image are image. Define

image

The supremum of V is called total variation of image on image denoted by image.
When image, image is called a function of bounded variation on image, or image has a bounded variation on image.

Proposition B.1.1

A monotonic function is a function of bounded variation.

Proposition B.1.2

A function of bounded variation is bounded.

Proposition B.1.3

The sum, difference and product of two functions of bounded variation are still functions of bounded variation.

Proposition B.1.4

If both image and image have a bounded variation and image, then image is still a function of bounded variation.

Proposition B.1.5

If image is a finite function on image and image, then image.

Proposition B.1.6

The necessary and sufficient condition that function image has a bounded variation is that image can be represented by the difference of two increasing functions.

Proposition B.1.7

If image has a bounded variation on image, then image is finite almost everywhere on image, and is integrable on image, where image is the differential of image.

Proposition B.1.8

Any function of bounded variation can be represented by the sum of its jump function and a continuous function of bounded variation.

Proposition B.1.9 (Herlly’ Principle of Selection)

Define an infinite number image of functions of bounded variation on image, and denoted by image. If there is a constant image such that image and image, then a sequence image of everywhere convergent functions on image can be selected from F and its limit function image still has a bounded variation.

B.1.2. LS Integral

Definition B.2.1

image and image are two finite functions on image. Points of division on image are image. Choose any point image from each interval image and construct a sum as follows

image

When image, if the sum converges to the same limit image independent of the selection of image, then limit image is called imageintegral of image with respect to image denoted by

image

Proposition B.2.1

If image is continuous on image and image has a bounded variation on image, then image exists.

Proposition B.2.2

If image is continuous on image, image has differential image everywhere and image is image integrable (Riemann integrable), then

image

Proposition B.2.3

image is continuous on image and image has a bounded variation, then

image

where image.

Proposition B.2.4

If image is a function of bounded variation on image, image is a sequence of continuous functions on image and uniformly converges to a continuous function image, then image.

Proposition B.2.5

image is a continuous function on image. image on image converges to a finite function image. If image, image, then image.

Definition B.2.2

If image, image is measurable set and has its corresponding value image, then image is called a set function on image. Given image, when image have image, then image is called an absolutely continuous function, where image is the measure of image.
For countable mutually disjoint measurable sets image, have image, then image is called a completely additive set function.

Definition B.2.3

image is a bounded measurable function on image. image is a completely additive set function on image. Assume that image. Interval image is partitioned as follows

image

Define image on image and construct a sum as

image

If image and image have the same limit image independent of the selection of image, then image is called image integral (Lebesgue-Stieltjes integral) of image with respect to image.

B.1.3. Limit Under Integral Symbol

Proposition B.3.1

image is a sequence of measurable functions on image and converge in measure to image. If there exists integrable function image such that image, image, then

image

Definition B.3.1

Assume that image is a family of integrable functions on image. If for image, there exists image, when image and image, for all image, image uniformly holds, image is called absolutely equicontinous integral on image.

Proposition B.3.2 (Vitali Theorem)

A sequence image of functions converges in measure to image on image, image is integrable on image and image has absolutely equicontinuous integral on image, then image is integrable on image and

image

Proposition B.3.3

image is a sequence of integrable functions on a measurable set image. For image, image is measurable, if image holds, then image has absolutely equicontinuous integral.

Corollary B.3.1

Assume that image is a sequence of integrable functions and image is an integrable function on a measurable set image. For any measurable set image, if

image

then image has absolutely equicontinuous integral on image.

Proposition B.3.4

image is a sequence of integrable functions on image and converges in measure to an integrable function image, then image (e is measurable), we have

image

The necessary and sufficient condition of the above result is that image has absolutely equicontinuous integral on image.

Proposition B.3.5 (Vallee-Poussin Theorem)

image is a family of measurable functions on a measurable set image. If there is a positive increasing function image, image, such that image and for image, have image, where image is a constant independent of image, then each image is integrable on image and image has absolutely equicontinuous function.

Proposition B.3.6

If image, is a family of functions on image having absolutely equicontinuous integral, then there exists a monotonically increasing function image such that image and image, where image is a constant independent of image.

Proposition B.3.7

image is an integrable function on image. If image, have image, then image (image is zero almost everywhere).

B.2. Central Limit Theorem

image are independently random variables. Let

image

Proposition B.2.1

image is an independently random variable. If image, the following formula is satisfied

image

where image is the distribution function of image, then when image, for image the following formula uniformly holds

image

Corollary B.2.1

image is image and has a non-zero variance, then when image, for image the following formula uniformly holds

image

where, image is its mean and image, image is its variance.

Proposition B.2.2

image is an independently random variable. If there exists a positive constant image such that when image,

image

then when image, for image, the following formula uniformly holds

image

Definition B.2.1

image is a discrete random variable. If there exist constants image such that all possible values of image can be represented by form image, where image, then image is called having sieve distribution, or image is a sieve variable.

Proposition B.2.3

image is an i.i.d. sieve random variable. If it has finite mean and variance, then when image, for image image the following formula uniformly holds

image

where, image, image.

Proposition B.2.4

image is image and has finite mean and variance. When image ( image is a fixed integer) let the distribution density function of image be image. Then, the necessary and sufficient condition that image, for image the formula image uniformly holds, is that there exists an integer image such that image function image is bounded.

B.3. Statistical Inference

B.3.1. SPRT Method

Definition 3.1.1

image is image and its distribution depends on parameter image, denoted by image.
A hypothesis testing problem: the simple null hypothesis image and the simple alternative hypothesis image. Let

image

image

The testing procedure is the following
Given constants image and image. Assume that image is the first observation of the subsample. Calculate image.
If image, then stop the observation and reject the null hypothesis image.
If image, then stop the observation and accept the null hypothesis image.
If image, then continue to get the second observation image.
Generally, if from the image-th observation the ‘stopping decision’ cannot be made, then continue to get the n-th observation image and calculate image.
If image, then stop sampling and reject image.
If image, then stop sampling and accept image.
If image, then continue sampling.
The above testing procedure is called Sequential Probability Ratio Test denoted by SPRT. Constants image and image are called the stopping boundaries of SPRT.

Proposition 3.1.1

If image stops with probability 1, its stopping boundaries are constants image and image, and significance level is image, then

image

Proposition 3.1.2

If image stops with probability 1, stopping boundary image and significance level image, then image.
Let

image

image

image

The stopping rule of image is the following.
If image, then reject image.
If image, then accept image.
If image, then continue sampling.

Proposition 3.1.3

If for a given parameter image, have image, where image, then there exist image, image and image such that

image

where, N is the stopping variable of image.

Proposition 3.1.4

Assume that image. If for image, have image, then image.

Proposition 3.1.5

image is i.i.d., image is a measurable function and image. Let N be a stopping variable and image. If image, then

image

Especially, if image, then

image

image

Proposition 3.1.6

Assume that image. For a image with stopping probability one and significance level image, the following formula holds

image

Or approximately,

image

Proposition 3.1.7

For simple null hypothesis image and simple alternative hypothesis image testing, among the testing methods, including sequential and non-sequential, that have image (reject image)image, image (accept image)image and image, the image with significance level image has the minimums of image and image.

B.3.2. ASM Method

3.2.1. Normal Distribution

image is i.i.d and its distribution function is image, image, image. Given credibility probability image. When image is known, there exists a fixed size of samples image, where image is the minimal integer satisfying the following formula

image

where image, image is a normal function, i.e., image. Then image, have

image(II.1)

where

image

When image is unknown, define a sampling process and assume that image is its stopping variable (when sampling stops Formula (II.1) holds). If image satisfies the following formula

image

Then the process is called asymptotically efficient. The corresponding method is called asymptotically efficient testing method with fixed width of the mean confident interval, denoted by ASM. The distribution of xi is assumed to be image.

Definition 3.2.1

Let n1, n2image. For each image, calculate image. Define stopping variable image as the minimal integer satisfying the following formula

image(II.2)

where, image is a series of positive constants and converges to image, image.

Proposition 3.2.1

Assume that image is a stopping variable defined by Formula (II.2). Then, we have the following properties.
(1) image
(2) If image, then image and image
where, symbol a.s means almost everywhere.
(3) image, image holds
(4) image
(5) image
(6) image

Proposition 3.2.2

In Formula (II.2), letting image and assuming that image is the corresponding stopping variable, then image, have

image

Proposition 3.2.3

In Formula (II.2), letting image, n1image, then for a finite image such that for image, image.

B.3.2. General Cases

Definition 3.2.2

Define image as the minimal integer satisfying the following formula

image(II.3)

where, image a series of positive constants and converges to image, image.

Proposition 3.2.4

Assume that image is a series of positive random variables image and image. Let image be a series of constants satisfying the following condition

image

For image, define image as the minimal integer satisfying the following formula

image

Then, image is a non-decreasing stopping variable of t and
(1) image
(2) image
(3) image
(4) image.
If image again, then image.

Proposition 3.2.5 (Chow-Robbins Theorem)

Assume that image is a stopping variable defined by Formula (II.3). Then,
(1) image
(2) When image image monotonically, image monotonically a.s.
(3) image
If image again, then
(4) image
where, image is the variance of F and image is a set of all distribution functions having finite second moments.

Proposition 3.2.6

image is i.i.d., image and image. Let image. image is a positive random integer, image, and satisfies

image

Then, we have

image

where, image is a convergent in measure limit and image.
The above proposition is the extension of common central limit theorem. In the common theorem N is a constant variable but image is a random variable.

Proposition 3.2.7

Let image be a sequence of random variables satisfying the following properties
(1) There exist real number image, distribution function image and a series image of real such that for all continuous points of F the following formula holds

image

(2) image, there exists a sufficiently large image and sufficient small positive number c such that when image have

image

Let image be a sequence of ascending integers and image. Let image be a stopping variable, image and image. Then, for all continuous points of image, we have

image

The materials of Addenda B are from Hogg (1977), Gnedenko (1956), and Natanson (1955).
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