Samples
Sample (Specimen) is a part of the observation or survey, and the overall is all of the research objects.
The element to be examined in the overall, how many sample capacity is called in the sample.
If the water or other living tissue specimens used from the patients in the water or river water during the water quality test, the blood or other living tissue specimen taken from the patient is sample; and a whole well or a river A total of all the water, a whole body of a patient, or a tissue organ, is an overall. Such generals are existing, but other overalls are imaginary, but only one range in theory. For example, testing a batch of flu patients who originally treated the treatment of the influenza, which is just a sample. If the medication is affirmed, it is promoted, then therefore, all the flu patients treated under the same conditions are this overall. However, when the trial, this overall does not exist, it is imaginary.
The overall observation unit is usually a large amount of even unlimited, in practice, it is generally impossible or unnecessary to study each observation unit one by one. We can only take a part of the observation unit to actually observe or investigate research, based on the observation of this part of observation unit, then inference and estimates the overall situation. As mentioned above, the treatment of flu flu, the test treatment is only a small number of patients, and the conclusion is to be promoted to all, and a regular understanding of the efficacy of all flu patients. Therefore, the purpose of observing the sample is to inject the overall, which is the sample and the overall dialectical relationship.
Standard poor
Standard Deviation, most commonly used as measurements on Statistical Dispersion in probability statistics. Standard difference definition is a square root of the arithmetic average of the overall unit standard value and the average number of disperacted squares. It reflects the degree of dispersion between individuals in the group. The result of the distribution is measured in principle, in principle: is a non-negative value, which has the same unit as measurement data. A total standard deviation or a standard deviation of a random variable, and there is a difference between the standard deviation of a subset sample.
Standard poor is expressed as the degree of discrete of sample data. The standard deviation is the top square of the sample average variance, and the standard deviation is usually determined relative to the average of the sample data, usually in m ± SD, indicating how far is the average value of the sample average. As can be seen from here, the standard deviation is affected by extreme values. The smaller the standard difference, indicating that the data is getting more; the standard differential is large, indicating that the data is discrete. The size of the standard deviation is determined by the test. If a quiz is an academic quiz, the standard deviation is large, indicating that the degree of discrete of the student score is large, and it is more able to measure the level of academic level; if a test measurement is a certain psychological quality, standard deviation Small, indicating that the topic written is homogeneous, and this time is better at this time. The standard deviation is closely related to normal distribution: in normal distribution, 1 standard deviation is equal to 68.26% of the curve under normal distribution, 1.96 standard deviations are equal to 95% area. This has an important role in the value of the test score.
Analysis method
definition
sample deviation from the sample mean The standard variance measures the degree of dispersion of the array. The calculation formula of the sample standard is:
merge
to a complete measurement process, its measurement results are uncertain The degree is derived by respectively evaluating each sub-uncertainty; where the measurement repetition is one of the uncertain components inevitable during the measurement process. However, in actual work, the verification, calibration, inspection, etc. carried out in various metering verification activities, which involve the number of quantities (measured), so it is impossible to use the Beser Fa to evaluate each The subject (measure) is measured by the uncertainty of the measurement of repetitiveness.
To solve the measurement uncertainty assessment needs of a large amount of instrument in the measurement verification, it can directly use the results of the pre-assessment to evaluate the uncertainty of the measurement repeatability. The method is to take several samples, each sample calculates the sample difference between the sample, and then combines each experimental standard (or average), which is the consolidated sample standard, and finally consolidated sample standards. To calculate the uncertainty components of the inspection (measured) instrument.
The basic idea of the consolidated sample standard is: the measurement process in the statistical control state, the single measurement result of the measured X
The standard uncertainty calculation formula for each measurement point single measurement results is:
and each measurement point N-measurement average measurement results standard uncertainty calculation formula is:
application
with steel plate Scratches
Wine steel galvanized unit design annual output is 750,000 t, the unit has a strong continuity, high for surface quality, its products to produce household capacity, aluminized Zinc plate is dominated and has exported to domestic and foreign markets. Since its in 2010, it has experienced a long process in solving steel scratches. Sources of scratching defects mainly include raw material substrates, mechanical scraping, speed mismatch, etc. As the accumulation of technical experience, the defects brought by the raw material substrate can be gradually identified, and the scratches produced by the zinc-galvanized line itself have lack of judgment methods. The roll surface scratches are mainly due to the mutual slip between the strip and roll surfaces, the main reason has a roller diameter, the roller surface projection, and the rotational speed deviation. How to determine the scratches caused by speed deviation, how much the deviation value can be scratched, and a new analysis identification method is required. Chen Dynasty, etc., through the exploration of research, using the sample standard deviation theory to the analysis, launched a set of analytical methods for this defect, and can qualitatively and timelyly eliminate defective sources.
Precision pressure indicates the value of the value of the value of the value.
The precision pressure gauge has the simple structure, the characteristics of high cost performance, long-term use in industrial and agricultural production And research tests, even used as standard equipment for verifying general pressure gauges. However, in conventional metering verification, calibration, and testing, metering people typically ignore the uncertainty of their display errors, so that the instrument user or the detection person cannot determine the accuracy of its measurement data. The reason is mainly due to the analysis of the measurement of the uncertainty component of the measurement repetitiveness, which is extremely complicated due to the analysis of the uncertainty components of the measurement repetitiveness, and the amount of work required is too large.
Zhao Benyi et al, analyzes the commonly used precision pressure indicating the megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload megadownload The analysis method is compared to simplify the precision pressure representation of the value error uncertainty assessment process, thereby achieving rapid analysis of precision pressure represents the target error uncertainty.