CN103413065A - Sample number calculator for comparing incidence proportions of different groups - Google Patents
Sample number calculator for comparing incidence proportions of different groups Download PDFInfo
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- CN103413065A CN103413065A CN2013103937492A CN201310393749A CN103413065A CN 103413065 A CN103413065 A CN 103413065A CN 2013103937492 A CN2013103937492 A CN 2013103937492A CN 201310393749 A CN201310393749 A CN 201310393749A CN 103413065 A CN103413065 A CN 103413065A
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Abstract
The invention relates to a sample number calculator for obtaining the incidence rates or prevalence risks of groups in etiological investigations. The sample number calculator is composed of an input module, a calculating module and a display module, wherein a technical formula is run in the calculating module. The sample number calculator is an intelligent calculator, and can be conveniently used by professionals and nonprofessionals.
Description
Technical field
The present invention relates to a kind of counter, be specifically related to a kind of counter that obtains the sample size of population risk or ill risk for the aetiology investigation.
Background technology
Etiological study is one of substance of epidemiological study, often runs in epidemiology survey and research practice.The most significant step of etiological study is to determine associated significance,statistical between disease and hypothesis paathogenic factor.Determine disease and the relevance of hypothesis between paathogenic factor, need the colony under the effect of more this hypothesis factor and do not have the generation of colony's disease of this factor whether variant.In the situation that the cause of disease is clear and definite, need to determine that different factors are on the pathogenetic impact of epidemic disease.
In the Field of Animal Epidemic Disease Control real work, usually prevalence rate or the onset risk of certain epidemic disease of different regions are compared, look at whether there are differences, and wish to find out the reason that causes this species diversity to exist; Or implement in the situation of different control measure the generation of epidemic disease or popular whether there are differences in colony.This need to or implement by sampling, to obtain sample the colony under different control measure from different areas, obtain corresponding ratio (being generally prevalence rate, onset risk in epidemiology), between compared proportions, whether there is the difference on statistical significance, thereby judge that this factor or control measure are on the pathogenetic impact of epidemic disease.
Traditional sample size is calculated and is mostly hand computation, the statistical function button is arranged in existing counter more, but this function is common statistical function, as read group total, square root etc., statistical formula for more complicated in statistics is calculated, need the professional very familiar to statistical formula, then use common counter with statistical function to calculate, acquired results is counted to table according to the fiducial interval in statistics and proofread and correct.The layman is difficult to carry out this work.
Summary of the invention
For the problems referred to above, one of purpose of the present invention is to provide a kind of sample size computing equipment of intelligence, this computing equipment specially in aetiology investigation for obtaining the calculating of the sample size that the different groups incidence of disease or ill risk need to extract.This mechanical discipline personnel and layman all can be easy to grasp and skilled use.
Another object of the present invention is to provide a kind of method of disease Study on Etiology, and in the method, amount of sampling calculates acquisition by above-mentioned computing equipment.
Computing equipment of the present invention comprises load module, amount of sampling computing module and display module.Wherein load module comprises confidence level, colony's 1 expection prevalence rate, colony's 2 expection prevalence rates and the input of power of a test and the input of numeral.The amount of sampling computing module is provided with the input end from described load module, goes to the output terminal of display module.This counter can also can pass through powered battery by AC-powered.
Morbidity ratio or ill ratio that in the aetiology investigation, an important job is the comparison different groups.
Find after deliberation, in certain check validity interval, whether compared proportions is variant, can calculate and obtain according to the approximate formula of following sample size:
Wherein:
N is the needed sample size of each group;
Z
αFor the 1-α of standardized normal distribution/2 percentiles, be the critical value of confidence level corresponding standardized normal distribution while being 1-α, z
0.06=1.96(annotates: this value is applicable to two-sided test or two-sided confidence interval);
Z
βFor (1-β) percentile of the standardized normal distribution relevant with check validity (power of a test) 1-β, for check validity (1-β), be for 80%, 85%, 90% and 95%, the z that it is corresponding
βValue is 0.84,1.04,1.28,1.64;
P
1The expection prevalence rate of colony 1
P
2The expection prevalence rate of colony 2
P is the mean value of 2 two expection prevalence rates of colony 1 and colony: (p
1+ p
2)/2
q=1-p
q
1=1-p
1
q
2=1-p
2
Random sampling from overall, by sample information, infer general characteristic, is not can run into such problem in actual applications: whether a certain sample rate come from certain known rate overall? are two different sample rates unequal overall from rate? answer such problem, need to solve with test of hypothesis.Test of hypothesis, claim again significance test, is to utilize small probability reduction to absurdity thought, from the opposite (H of problem
0) the indirect judgement of the setting out problem (H that will solve
1) whether set up.Namely at hypothesis H
0Under the condition of setting up, calculate test statistics, then according to the P value obtained, judge.The deduction conclusion of making according to the P value has probability, so its conclusion can not be entirely true, and two class mistakes may occur.
Type Ⅰ error: be to have refused correct null hypothesis H
0, the mistake that this class " is abandoned true " is called type Ⅰ error.The inspection level that we often say, the maximal value of type Ⅰ error probability is violated in the permission of predesignating exactly, means with α.As stipulate α=0.05, mean and work as H
0Set up refusal H
0The time, the such mistake of generation is on average arranged in 100 checks 5 times in theory.
Type Ⅱ error: be to have accepted actual invalid null hypothesis H
0, the mistake of this class " type B error " is called type Ⅱ error.Its probability size means with β, and β only gets single tail, and its size is general unknown, must, when knowing two overall differences, α and n, just can calculate.
The check validity is 1-β, and its meaning totally truly has difference for working as two, and inspection level α can find the ability of this difference in accordance with regulations.As 1-β=0.9, two totally truly have difference if mean, in theory in average every 100 checks, have can show that difference has the conclusion of statistical significance 90 times.
Two sample rates be relatively available u-test, also available χ
2Check, but real work more application χ often
2Check.χ
2Check is with χ
2Be distributed as theoretical foundation, only have parameter, i.e. a degree of freedom.Chi-square value and inspection level P value have corresponding relation, χ
2Be worth greatlyr, the P value is less; Otherwise, χ
2Be worth littlely, the P value is larger.χ
2During check, first calculate the χ of test statistics
2Value, then look into χ by degree of freedom
2The dividing value table, determine the P value, and the last and definite inspection level of institute compares, thereby judges whether difference is remarkable.
Embodiment
Below, with reference to accompanying drawing, sample sample calculation device according to the present invention is described.
Structure:
As shown in Figure 1, counter of the present invention has load module 1 and display module 3.Described load module is comprised of various buttons, and various buttons comprise confidence level (CL) key, colony's 1 expection prevalence rate (p1) key, colony's 2 expection prevalence rate (p2) keys, permissible error (α) key and power of a test (β) key and ten digital keys, decimal key (.), cancel button (UNDO) key, acknowledgement key (ENTER) and directionkeys.
Confidence level (CL%) key: press this key, CL appears in display screen:, by the corresponding confidence level of ten numerical key inputs, as 95%, input 95, press acknowledgement key and confirm.
Colony's 1 expection prevalence rate (p1) key: press this key, p1 appears in display screen:, by the corresponding expection of ten numerical key inputs prevalence rate, as 15%, input 0.15, press acknowledgement key and confirm.
Colony's 2 expection prevalence rate (p2) keys: press this key, p2 appears in display screen:, by the corresponding expection of ten numerical key inputs prevalence rate, as 10%, input 0.10, press acknowledgement key and confirm.
Permissible error (α) key: press this key, α appears in display screen:, by the corresponding permissible error of ten numerical key inputs, as 5%, input 5, press acknowledgement key and confirm.
Power of a test (β) key: press this key, β appears in display screen:, by the corresponding permissible error of ten numerical key inputs, as 10%, input 10, press acknowledgement key and confirm.
Cancel button (UNDO) key: press this key, can delete the data that are strayed into.
The left and right scroll key of directionkeys is realized advancing of display page and is retreated.
The display screen of display module 3 correspondences shows the numeral that corresponding various buttons are pressed.
Function:
Below, the function composing of counter is described.
Fig. 2 is the block diagram of calculator function structure, as shown in the figure, sample sample calculation utensil has input part 3, display part 4, ROM(Read only Memory) 5, the function parts such as RAM (Random Access Memory) 6 and CPU (Central Processing Unit) 7, each function part is connected by bus 9.
ROM5 preserve to sample sample calculation device in related various setting up an office process and various programs that the operations such as calculation process of concrete amount of sampling computing formula are relevant and be used to the program that realizes the various functions that the sample calculation device has etc.In the present embodiment, store sampling sample size calculation procedure, from ROM5, read the program ROM5 by CPU7, be performed after in RAM6, launching.
RAM6 is the storer that temporarily keeps writing at any time the various programs that CPU7 carries out or relate to data that these programs carry out etc.RAM6 stores by the information of each parameter of user input or the operation result of data or respective sample amount computing formula etc. such as having in the present embodiment.
The CPU7 processing carried out based on established procedure corresponding to the indication of inputting, carry out each to the indication of function part or the transmission of data, specifically, CPU7 reads out in the program of preserving ROM5 according to the operation signal of inputting from input part 3, according to this program, carry out and process, thereby CPU7 is used for the display control signal of Graphics Processing result to 4 outputs of suitable display part, and shows corresponding demonstration information.
Embodiment
Operational instances 1:
Below, use flow process and picture conversion shown in Figure 3, the sample amount of sampling counter of operational example carry out to(for) CPU7 describes, and shows user's operation in the left side of figure, the picture in the right side of figure shows display screen.
Before user's operation push-button, carry out the standby processing:
(1) according to the purpose of investigation, collect respondent's essential information, and press the follow procedure operation.
(2) press the confidence level key, display screen shows CL:;
(3) confidence level of passing through ten numerical key input selections is as 95%, and display screen shows CL:95, presses acknowledgement key and confirms;
(4) press colony's 1 expection prevalence rate key, display screen shows P1:;
(5) by ten numerical keys, input corresponding prevalence rate as 15%, input 0.15, display screen shows P1:0.15, presses acknowledgement key and confirms;
(6) press colony's 2 expection prevalence rate keys, display screen shows P2:;
(7) by ten numerical keys, input corresponding prevalence rate as 10%, display screen shows P2:0.10, presses acknowledgement key and confirms;
(8) press the power of a test key, display screen shows β:;
(9) by ten numerical keys, input corresponding power of a test as 80%, input 80, display screen shows β: 80, and press acknowledgement key and confirm;
Display shows that the operation result of CPU7 is as 685.
Example 2:
Certain county is that the raising dairy cattle industry is comparatively flourishing, is also the place that the cloth disease is comparatively serious.Local raising dairy cattle mainly comprises two kinds of modes, and a kind of be large-scale cultivation, and namely the cattle farm scale is large, and the milking equipment of oneself is arranged, and this has the animal doctor, and oneself is bred, management regulation and being isolated from the outside; Another kind is milk cattle cultivating community or village specializing in a certain trade, and namely a plurality of milk cattle cultivatings family flocks together, and shares milking equipment, provides service by local breeding station and animal doctor.Toward the sick testing result of cloth, cloth sick positive rate in estimation scale field is in 4% left and right according to this, and the sick positive rate of other feeding manner milk cow cloth is about 7%.If confidence level 95%, guarantee to need to extract how many samples in situation that 90% power of a test determines that difference exists?
Before user's operation push-button, carry out the standby processing:
(1) press the confidence level key, display screen shows CL:;
(2) by the confidence level 95% of ten numerical key input selections, display screen shows CL:95, presses acknowledgement key and confirms;
(3) press colony's 1 expection prevalence rate key, display screen shows P1:;
(4) by ten numerical keys, input corresponding prevalence rate as 7%, input 0.07, display screen shows P1:0.07, presses acknowledgement key and confirms;
(5) press colony's 2 expection prevalence rate keys, display screen shows P2:;
(6) by ten numerical keys, input corresponding prevalence rate as 4%, display screen shows P2:0.04, presses acknowledgement key and confirms;
(7) press the power of a test key, display screen shows β:;
(8) by ten numerical keys, input corresponding power of a test as 90%, input 90, display screen shows β: 90, and press acknowledgement key and confirm;
Display shows that the operation result of CPU7 is as 1211, and namely the sample size of each colonial need extraction is 1211 cow heads.
At this, describe the preferred embodiment of the present invention, comprised the best pattern of the realization invention that the inventor is known.After reading above-mentioned description, the variation of those preferred implementations will be apparent for persons skilled in the art.The inventor expects that those of skill in the art can adopt these variations suitably.Therefore, the present invention includes all modifications and the equivalent of the theme of stating that governing law allows in appended claims, in addition, present invention resides in any combination of the above-mentioned element in all possible variation.Unless have in other different explanations or context to have clearly at this, negate.
The accompanying drawing explanation
Fig. 1: the front view (FV) that is sample amount of sampling counter
Fig. 2: mean the block diagram that sampling sample size counter summary forms
Fig. 3: the schematic diagram that is the picture conversion in present embodiment
Claims (3)
1. a counter that obtains the sample size of population risk or ill risk for the aetiology investigation, is characterized in that described counter comprises load module, computing module and display module, and the computing formula of moving in wherein said computing module is
Wherein:
N is the needed sample size of each group;
Z
αFor the 1-α of standardized normal distribution/2 percentiles, be the critical value of confidence level corresponding standardized normal distribution while being 1-α,
P
1The expection prevalence rate of colony 1
P
2The expection prevalence rate of colony 2
P is the mean value of 2 two expection prevalence rates of colony 1 and colony: (p
1+ p
2)/2
q=1-p
q
1=1-p
1
q
2=1-p
2。
2. counter as claimed in claim 1, is characterized in that described load module comprises confidence level (CL) key, colony's 1 expection prevalence rate (p1) key, colony's 2 expection prevalence rate (p2) keys, permissible error (α) key and power of a test (β) key and ten digital keys, decimal key (.), cancels button (UNDO) key, acknowledgement key (ENTER) and directionkeys.
3. the method for a disease Study on Etiology, in the method, the amount of sampling of sample calculates acquisition by the described counter of any one in claim 1-2.
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| CN103413065B CN103413065B (en) | 2016-11-23 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1424651A (en) * | 2002-04-19 | 2003-06-18 | 刘振民 | Generation 3 counting tools |
| CN102184470A (en) * | 2011-04-28 | 2011-09-14 | 上海同城信息科技有限公司 | Method and device for processing selected information of sample points in land price survey |
| WO2012151212A1 (en) * | 2011-05-01 | 2012-11-08 | University Of Rochester | Multifocal hepatocellular carcinoma microrna expression patterns and uses thereof |
| CN102855384A (en) * | 2012-07-27 | 2013-01-02 | 中国农业科学院油料作物研究所 | Quantitative evaluation method for peanut aflatoxin B1 pollution on human health risk |
-
2013
- 2013-09-02 CN CN201310393749.2A patent/CN103413065B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1424651A (en) * | 2002-04-19 | 2003-06-18 | 刘振民 | Generation 3 counting tools |
| CN102184470A (en) * | 2011-04-28 | 2011-09-14 | 上海同城信息科技有限公司 | Method and device for processing selected information of sample points in land price survey |
| WO2012151212A1 (en) * | 2011-05-01 | 2012-11-08 | University Of Rochester | Multifocal hepatocellular carcinoma microrna expression patterns and uses thereof |
| CN102855384A (en) * | 2012-07-27 | 2013-01-02 | 中国农业科学院油料作物研究所 | Quantitative evaluation method for peanut aflatoxin B1 pollution on human health risk |
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