concept: secondary sampling inspection
an extension of primary sampling inspection, which requires that at most two samples are taken from a batch of products to make a conclusion on whether the batch is accepted or not. When the first sample cannot determine whether the batch is accepted or not, the second sample is taken, and then the results of the two samples are used to determine whether the batch is accepted or not.
Scheme:
Counting sampling scheme The quality characteristics of some products, such as the number of defective solder joints, the number of defective products tested and whether they are qualified or not, can only be measured by discrete scales. The method of measuring samples by discrete scales is called counting sampling inspection. In counting sampling inspection, the quality of unit products is measured by counting, and the quality of whole batch products is generally measured by average quality. Counting sampling inspection scheme can be divided into: standard counting primary sampling scheme, counting selection primary sampling scheme, counting adjustment primary sampling scheme, counting continuous production sampling scheme, secondary sampling scheme and multiple sampling schemes. ① One-time sampling inspection scheme One-time sampling inspection scheme is the simplest counting sampling inspection scheme, which is usually represented by (n, n, c). That is to say, n pieces are randomly selected from the products submitted for inspection in batches of n, and a qualified judgment number c is specified in advance. If it is found that there are D unqualified products in N, when D is less than or equal to C, the batch of products is judged to be qualified and accepted; When d> C, the batch of products is judged to be unqualified and rejected. For example, when N= 1, n=1 and C=1, this one-time sampling scheme is expressed as (1, 1, 1). Its meaning means that 1 pieces are randomly selected from the products submitted for inspection in batches of 1 pieces. After inspection, if the number of unqualified products in these 1 pieces is or 1, the batch of products is judged to be qualified and accepted; If more than two of the 1 products are found to be unqualified, the batch of products is judged to be unqualified and rejected.
② compared with the primary sampling scheme, the secondary sampling scheme includes five parameters, namely (n, n1, n2, C1, C2). Where: n1 refers to the size of the first sample; N2— the size of the second sample is extracted; C1 refers to the number of unqualified judgments when the first sample is taken; C2 refers to the number of unqualified judgments when the second sample is taken. The operation procedure of the second sampling scheme is: n1 products are randomly selected for inspection from a batch of products with a batch of N submitted for inspection. If unqualified product d1 is found in n1 products, if D1 is less than or equal to C1, the batch of products is judged to be qualified and accepted; If d1> C2, judging that the batch products are unqualified and rejecting them; If C1 C2, the batch product is judged to be unqualified and rejected. For example, when N=1, n1=4, n2=6, C1=2, C2=4, this secondary sampling scheme can be expressed as (1, 4, 6; 2，4）。 It means that the first sample n1=4 pieces is randomly selected from the products submitted for inspection in batches of 1 pieces. If the number of unqualified products in n1 is found to be d1, if D1 <: 2, the batch of products is judged to be qualified and accepted; If d1> 4, the batch of products is judged to be unqualified and rejected; If it is 2 4, the batch of products is judged to be unqualified and rejected.
what does Re mean in sampling inspection?
context? Generally, re means in respect of (that is, about)
What is sampling inspection? Please answer
Sampling inspection, also known as sampling inspection, is a statistical method and theory to randomly select a small number of products (samples) from a batch of products for inspection to judge whether the batch of products is qualified or not. It differs from comprehensive inspection in that the latter needs to inspect the whole batch of products one by one and pick out the unqualified products, while sampling inspection infers the quality of the whole batch of products according to the inspection results of the products in the sample. If it is concluded that the batch of products meets the pre-specified qualification standards, it will be accepted; Otherwise it will be rejected. Therefore, a batch of products that are considered qualified after sampling inspection may also contain some unqualified products.
Basic terms of sampling inspection
1. Batch: A certain number of products manufactured under the same conditions are called "batches". A series of batches produced continuously in the production process of 5M1E (namely, people, machines, materials, methods, measurement and environment) are called continuous batches; A batch that cannot be defined as a continuous batch is called an isolated batch. 5M1E refers to: ① man, including his quality consciousness, sense of responsibility, technical and professional level, operating proficiency and physical condition. (2) the equipment (machine), whether it has been tested and corrected, whether the operation condition is normal, whether there is a strict management and use system, and so on. ③ Whether the material including reagents, medicines and experimental animals are standard and effective. Whether the reagent drugs are marked with the manufacturer, expiration date and content; Whether the source, strain, grade, age, sex, adaptation and feeding of experimental animals are clear. (4) the measurement (measure), including the accuracy of the test instrument and measurement methods, etc., whether there is a clear regulation and strictly enforced. ⑤ method, including whether the technological route, operating rules and organizational management methods are standardized, standardized and programmed; Whether the post responsibility system and assessment are sound; ⑥ environment, including temperature, humidity, dew point, dust content, noise, vibration, lighting, hygiene and other conditions that have an impact on product quality, and whether the control conditions have been controlled. 2. Unit product: The basic unit divided for the need of sampling inspection is called unit product. 3. Batch size and sample size: Batch size refers to the number of products per unit contained in a batch, which is represented by n.. Sample size refers to the number of products per unit in a randomly selected sample, which is represented by n. 4. Samples and sample units: The unit products extracted from the inspection batch for inspection are called sample units. The whole sample unit is called a sample. Sample size refers to the number of sample units contained in the sample. 5. Qualified quality level (AQL) and unqualified quality level (RQL): The average upper limit value of continuous submission of inspection batches that is considered acceptable in sampling inspection is called qualified quality level. The process average refers to the average quality of a series of initial inspection batches, which is expressed by the number of unqualified products per hundred units or the number of unqualified products per hundred units; The specific value is determined by both parties through consultation, and is generally represented by AQL symbol; In sampling inspection, the lower limit value of batch quality that is considered unacceptable is called unqualified quality level, which is represented by RQL symbol. 6. Inspection and inspection level (IL): The process of comparing unit products with technical requirements by measurement, test or other methods is called inspection. There are normal inspections, tightened inspections and relaxed inspections. 7. Two types of risks A and β: due to the randomness of sampling inspection, the original qualified batch is misjudged as the probability of rejection, which is unfavorable to the producer, so it is called the first type of risk or the producer's risk, and is represented by A; And the original unqualified batch may be misjudged as acceptable, which will be unfavorable to the user. This probability is called Class II risk or user risk, which is expressed as β. 8. The sample size or sample size series of the sampling inspection scheme is combined with the judgment array, which is called the sampling scheme. The judgment array refers to the combination of qualified judgment numbers and unqualified judgment numbers or qualified judgment numbers and unqualified judgment numbers. Sampling schemes include primary, secondary and fifth sampling schemes. One-time sampling scheme refers to a sampling scheme composed of sample size n and decision array (Ac, Re). Ac is the qualified judgment number. When the batch is judged to be qualified, the maximum number of nonconforming products (D) contained in the sample is called the qualified judgment number, also known as the received number (d≤Ac). Re is the number of unqualified judgment, which is the minimum number of unqualified products contained in the sample when the batch is judged unqualified, also known as the number of rejected products (d≥Re). The subsampling scheme refers to a scheme consisting of a first sample size n1, a second sample size n2,.. and a decision array (Ac1; Ac2，Re1; Re2) A sampling scheme composed by combining them. The quintuple sampling scheme refers to the sampling scheme composed of the first sample size n1, the second sample size n2, … the fifth sample size n5 and the decision array (A1, A2, A3, A4, A5, R1, R2, R3, R4, R5).
what is statistical sampling inspection
statistical sampling inspection is random sampling inspection, which uses samples randomly selected from batches or processes to inspect the quality of batches or processes. That is, according to the statistical laws of variation (distribution/dispersion/fluctuation/...), such as normal distribution, binomial distribution, ..., a series of (systematic) operations to randomly select a sample from the population (batch) to estimate whether the overall characteristics (quality) meet the specified requirements.
what is sampling? What is the scope of application of sampling inspection?
Sampling refers to sampling a small quantity of finished products, but it depends on your company's inspection standards, and it should be selected according to a few percent probability. The scope of sampling inspection is about people's livelihood, which is too wide.
What does population sampling inspection mean?
This is the work that the Bureau of Statistics has to do every year. It is to randomly select several communities and villages in an area to conduct a population survey. Can accurately understand the population changes, birth rate, mortality and so on.
what does' sampling inspection' mean in construction engineering?
The meaning of' sampling inspection' in construction engineering
is to inspect materials according to some requirements of quality inspection stations, such as reinforced concrete and so on. According to the approved construction plan, design documents (construction drawings) and engineering contract, the construction organization refers to the activities of planning, organizing and controlling the construction and installation tasks from the start to the completion and delivery.
according to the characteristics of the project itself, the five elements of manpower, capital, materials, machinery and construction methods are arranged scientifically and reasonably, so that the organized, planned and orderly construction can be realized within a certain period of time, and the project can be of good quality, fast progress and low cost. For a specific project, after the construction method and scheme are selected, time organization, space organization and resource organization should be carried out, which are the three most important organizations of construction organization.
in short, construction organization refers to the organization of construction workers, construction machinery, building materials and components directly used in the construction process, that is, the organization of basic construction process and non-basic construction process and ancillary business, which includes both the construction of formal projects and the construction of temporary facilities.
construction organization is the main part of project construction management, and its position and function are directly related to the operating results of the whole project. In other words, it narrows the production management scope of a construction enterprise to a construction site (region) to manage each project.