Sparse distributed memory: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
← Older editNewer edit →
en>Jonesey95
en>DoktorRF
→Uses: Removed variable key as per previous attempt
Line 1: Line 1:
[[File:Log DiagnosticOddsRatio.png|thumb|log(Diagnostic Odds Ratio) for varying sensitivity and specificity]]


{{context|date=January 2012}}
The '''diagnostic odds ratio''' is a measure of the effectiveness of a [[diagnostic test]].<ref name="Glas 2003">Afina S. Glas, Jeroen G. Lijmer, Martin H. Prins, Gouke J. Bonsel, Patrick M.M. Bossuyt. The diagnostic odds ratio: a single indicator of test performance. Journal of Clinical Epidemiology, 56 (2003), 1129-1135.</ref> It is defined as the ratio of the odds of the test being positive if the subject has a disease relative to the odds of the test being positive if the subject does not have the disease.


== Definition ==
As you can see from the above article, it is easy to understand how to make money online when you get the knowledge through great tips. You can join the millions of people worldwide who make money each day, if you [http://www.comoganhardinheiro101.com/category/opcoes-binarias/ como ficar rico] pay close attention to the tips that you have just read. Making money online is a skill, and if you continue to study good tips and ideas such as these, there is no reason why you cannot make lots of money online. <br><br><br>that's a lie. Don't fall prey to these types of websites and always read the reviews before joining. Talking to experts in their field can help you to use [http://www.comoganhardinheiro101.com/como-ganhar-dinheiro-pela-internet/ como ganhar dinheiro] the Internet successfully. Try to network with people who do what you want to do. Doing these things can help give you an advantage over your competition.<br><br>If you want to do something creative, consider ways to create viral videos. Brainstorm ideas that you think are rip riotously hilarious, then start putting them into action. Post them on YouTube, turn on ads and, if they work, watch the money start rolling in! Learn about marketing to see how you can get them even more popular. [http://www.comoganhardinheiro101.com/ferramentas/ como ficar rico] If  ganhar [http://www.comoganhardinheiro101.com/slide-central/ ganhe dinheiro] you know how to prepare taxes, you can earn money online. Apply for the necessary government licenses and then begin offering your services online. Many of today's top producers work from home with only their laptop and an email address. For best results, continually advertise your services throughout the year.<br><br>Medical transcription can be a good way to make money online as a full time career. Formal training is required, and this can be costly. Additionally, it is necessary to have good computer and transcription equipment that works reliably. A great deal of work is available for people who are able and willing [http://www.comoganhardinheiro101.com/opcoes-binarias/ ganhando dinheiro na internet] to invest in training and good equipment. Pay is quite substantial. You can sell your wares on the Internet to make money. Certain sites will help you to do your selling. You can personalize the t-shirts for your client. You can advertise by putting fliers up around the neighborhood or by using Craigslist.<br><br>
The diagnostic odds ratio is defined mathematically as:


:<math>\text{Diagnostic odds ratio, DOR} = \frac{TP/FN}{FP/TN}</math>
Don't buy every book about making money online. Most of the time, these books are sold by people whose claim to fame is that they are teaching people how to make money [http://www.comoganhardinheiro101.com/tag/opcoes-binarias/ como ganhar dinheiro] online. Before you buy an e-book or book about making money, make sure that you know a little about the author, and that you have seen testimonials about the book.<br><br>To really make money online, consider setting up your own site and having all the control. You could sell things as an affiliate or offer professional services, among many other things. While working for others can earn you a nice income, there's nothing like raking in all the profits and calling [http://www.comoganhardinheiro101.com/testemunhos/ ganhar dinheiro pela internet] all the shots yourself! As stated above, there are lots of ways to increase your online income. Use these suggestions to help you get started. You will be amazed at how quickly the money can add up. Come back to this page and others like it to continue growing your online work portfolio as you go.<br><br>Affiliate marketing can be a good way to earn money online if you have a lot of time and energy to spend on website setup and promotion. Affiliate marketers market the products of others in a number of ways.  If you are you looking for more information about [http://comoconseguirdinheiro.comoganhardinheiro101.com ganhar dinheiro] review comoconseguirdinheiro.comoganhardinheiro101.com You can create a website and promote [http://www.comoganhardinheiro101.com/testemunhos/ como ganhar dinheiro na internet] it. Creating a blog or posting on the blogs of others in your niche is also an excellent way to share product information. Making smart use of social media and e mail marketing are also possibilities for successful affiliate marketing.<br><br>Take advantage of paid per post if you have extra time and need to make money online. People will need you to make posts on their site to promote a product or give a good review, which will help them in the long run. In return, they will pay you a nice sum. Do you enjoy [http://www.comoganhardinheiro101.com/?p=4 ganhe dinheiro na internet] writing? If so, you can make cash by becoming a freelance writer. Just be aware that most freelance writing sites prefer writers with experience. But, there are other sites that will hire you if you pass a test. It's a bonus if you have knowledge on particular subjects. <br><br><br>Manage your time wisely when you are trying to make money online. You may have a real-world job, which means you have to budget time wisely. Set a schedule that will allow you enough time to balance the two. Also make sure that you are being efficient in that time, so you don't run into stress [http://www.comoganhardinheiro101.com/?p=71 como conseguir dinheiro] about working online. Becoming a ghost writer is a great way to earn money online. There are people who need content for their websites, but who lack good writing skills. You can write for them and earn money for what you write. Many people are earning a good income writing for others this way.<br><br>Several websites out there pay for people to do tasks that cannot be handled by a computer. It might be flagging inappropriate activity or finding the name of a business on a receipt. These tasks require human [http://comoganhardinheiropelainternet.comoganhardinheiro101.com/ intelligence] to find the answer. They are reasonably simple to perform and can provide you with some extra [http://www.comoganhardinheiro101.com/?p=8 como ganhar dinheiro na internet] money. Translate documents if you are fluent in a second language and want to make money on the side. Check out the freelancing sites to find people who will need things altered into a different language. This can be anyone from a large corporation to an individual who wants to translate something for a friend.<br><br>To really make money online, consider setting up your own site and having all the control. You could sell things as an affiliate or offer professional services, among many other things. While working for others can earn you a nice income, there's nothing like raking in all the profits and calling [http://www.comoganhardinheiro101.com como ganhar dinheiro] all the shots yourself! As stated above, there are lots of ways to increase your online income. Use these suggestions to help you get started. You will be amazed at how quickly the money can add up. Come back to this page and others like it to continue growing your online work portfolio as you go.<br><br>Manage your time wisely when you are trying to make money online. You may have a real-world job, which means you have to budget time wisely. Set a schedule that will allow you enough time to balance the two. Also make sure that you are being efficient in that time, so you don't run into stress [http://www.comoganhardinheiro101.com/?p=71 como conseguir dinheiro] about working online. Becoming a ghost writer is a great way to earn money online. There are people who need content for their websites, but who lack good writing skills. You can write for them and earn money for what you write. Many people are earning a good income writing for others this way.<br><br>


where <math>TP</math>, <math>FN</math>, <math>FP</math> and <math>TN</math> are the number of true positives, false negatives, false positives and true negatives respectively.<ref name="Glas 2003" />
If you want to do something creative, consider ways to create viral videos. Brainstorm ideas that you think are rip riotously hilarious, then start putting them into action. Post them on YouTube, turn on ads and, if they work, watch the money start rolling in! Learn about marketing to see how you can get them even more popular. [http://www.comoganhardinheiro101.com/tag/opcoes-binarias/ ganhar dinheiro na internet] If you know how to prepare taxes, you can earn money online. Apply for the necessary government licenses and then begin [http://Ganhardinheiropelainternet.Comoganhardinheiro101.com/ offering] your services online. Many of today's top producers work from home with only their laptop and an email address. For best results, continually advertise your services throughout the year.<br><br>If you're a performer, YouTube may help you earn income online. Make a brief video clip showcasing your talents. Are you a whiz with cosmetics? Make online tutorials that focus on makeup. Do you view yourself as a comedian? Why not film a brief comedy routine on hot news topics? When your videos have [http://www.comoganhardinheiro101.com/?p=10 ganhar dinheiro] been uploaded to the site, advertisements will be attached to your page and this will lead to payment. There are many ways you can make money online; all you need is some basic information. This article should have helped you get started. Use these tips to earn as much or as little as you need online.<br><br>that's a lie. Don't fall prey to these types of websites and always read the reviews before joining. Talking to experts in their field can help you to use [http://www.comoganhardinheiro101.com/caracteristicas/ ganhar dinheiro na internet] the Internet successfully. Try to network with people who do what you want to do. Doing these things can help give you an advantage over your competition.<br><br>If you have the ability to type quickly, you may consider transcription jobs. You need to have good headphones and the ability to keep up with what is being said. Often, the companies will have their own formatting guidelines. Familiarize yourself with these prior to beginning. Once you have, you can begin transcribing. What do you do? Do it for pay! A number of websites offer you points when you search through them and/or make purchases of items that you were planning to buy anyway. Take the points you earn and trade them for gift cards, gifts and sometimes even cash. Sites thatprovide this opportunity include Swagbucks and Mypoints.
 
=== Confidence interval ===
As an [[odds ratio]], the [[Natural logarithm|logarithm]] of the diagnostic odds ratio is approximately [[Normal distribution|normally distributed]].{{clarify|reason=give sample sizes/region where approximation is reasonable|date=January 2012}} The [[Standard error (statistics)|standard error]] of the log diagnostic odds ratio is approximately:
 
:<math>\mathrm{SE}\left(\log{\text{DOR}}\right) = \sqrt{\frac{1}{TP}+\frac{1}{FN}+\frac{1}{FP}+\frac{1}{TN}}</math>
 
From this an approximate 95% [[confidence interval]] can be calculated for the log diagnostic odds ratio:
 
:<math>\log{\text{DOR}} \pm 1.96 \times \mathrm{SE}\left(\log{\text{DOR}}\right)</math>
 
Exponentiation of the approximate confidence interval for the log diagnostic odds ratio gives the approximate confidence interval for the diagnostic odds ratio.<ref name="Glas 2003" />
 
== Relation to other measures of diagnostic test accuracy ==
The diagnostic odds ratio may be expressed in terms of the [[sensitivity and specificity]] of the test:<ref name="Glas 2003" />
 
:<math>\text{DOR} = \frac{\text{sensitivity}\times\text{specificity}}{\left(1-\text{sensitivity}\right)\times\left(1-\text{specificity}\right)}</math>
 
It may also be expressed in terms of the [[Positive predictive value]] (PPV) and [[Negative predictive value]] (NPV):<ref name="Glas 2003" />
 
:<math>\text{DOR} = \frac{\text{PPV}\times\text{NPV}}{\left(1-\text{PPV}\right)\times\left(1-\text{NPV}\right)}</math>
 
It is also related to the [[Likelihood ratios in diagnostic testing|likelihood ratios]], <math>LR+</math> and <math>LR-</math>:<ref name="Glas 2003" />
 
:<math>\text{DOR} = \frac{LR+}{LR-}</math>
 
== Rationale and interpretation ==
The rationale for the diagnostic odds ratio is that it is a single indicator of test performance (like [[Accuracy#Accuracy and precision in binary classification|accuracy]] and [[Youden's J statistic]]) but which is independent of [[prevalence]] (unlike accuracy) and is presented as an [[odds ratio]], which is familiar to medical practitioners.
 
The diagnostic odds ratio ranges from zero to infinity, although diagnostic odds ratios less than one indicate that the test can be improved by simply inverting the outcome of the test. A diagnostic odds ratio of exactly one means that the test is equally likely to predict a positive outcome whatever the true condition. Higher diagnostic odds ratios are indicative of better test performance.<ref name="Glas 2003" />
 
== Uses ==
'''Note:''' All the following uses are deprecated by more recent innovations in the meta-analysis of diagnostic test accuracy studies, namely the bivariate method<ref>Reitsma, Johannes B., et al. "Bivariate analysis of sensitivity and specificity produces informative summary measures in diagnostic reviews." Journal of clinical epidemiology 58.10 (2005): 982-990.</ref> and the hierarchical summary ROC (HSROC) method.<ref>Rutter, Carolyn M., and Constantine A. Gatsonis. "A hierarchical regression approach to meta‐analysis of diagnostic test accuracy evaluations." Statistics in medicine 20.19 (2001): 2865-2884.</ref>
 
The log diagnostic odds ratio is sometimes used in meta-analyses of diagnostic test accuracy studies due to its simplicity (being approximately normally distributed).<ref name="Gatsonis 2006">Constantine Gatsonis, Prashni Paliwal. Meta-analysis of diagnostic and screening test accuracy evaluations: methodologic primer. American Journal of Roentgenology 187(2), 271-281. 2006.</ref>
 
Traditional [[Meta-analysis|meta-analytic]] techniques such as [[inverse-variance weighting]] can be used to combine log diagnostic odds ratios computed from a number of data sources to produce an overall diagnostic odds ratio for the test in question.
 
The log diagnostic odds ratio can also be used to study the trade-off between sensitivity and specificity.<ref name="Moses 1993" /><ref name="Dinnes 2007">J. Dinnes, J. Deeks, H. Kunst, A. Gibson, E. Cummins, N. Waugh, F. Drobniewski, A. Lalvani. A systematic review of rapid diagnostic tests for the detection of tuberculosis infection. Health Technology Assessment, 11(3), 2007.</ref> By expressing the log diagnostic odds ratio in terms of the [[logit]] of the true positive rate (sensitivity) and false positive rate (1 &minus; specificity), and by additionally constructing a measure, <math>S</math>:
 
:<math>D = \log{\text{DOR}} = \log{\left[\frac{TPR}{(1-TPR)}\times\frac{(1-FPR)}{FPR}\right]} = \operatorname{logit}(TPR) - \operatorname{logit}(FPR)</math>
:<math>S = \operatorname{logit}(TPR) + \operatorname{logit}(FPR)</math>
 
It is then possible to fit a straight line, <math>D = a + bS</math>. If <var>b</var> ≠ 0 then there is a trend in diagnostic performance with threshold beyond the simple trade-off of sensitivity and specificity. The value <var>a</var> can be used to plot a summary [[Receiver operating characteristic|ROC]] (SROC) curve.<ref name="Moses 1993" /><ref name="Dinnes 2007" />
 
== Example ==
Consider a test with the following 2&times;2 [[confusion matrix]]:
{| class="wikitable"
|-
! rowspan="2" colspan="2" style="background:#fff; border-color:#fff #aaa #aaa #fff" |
! colspan="2" | Condition (as determined by “[[Gold standard (test)|Gold standard]]”
|-
! Positive
! Negative
|-
! rowspan="2" style="text-align:left" | Test<br />outcome
! Positive
| style="text-align: center" | 26
| style="text-align: center" | 12
|-
! Negative
| style="text-align: center" | 3
| style="text-align: center" | 48
|}
 
We calculate the diagnostic odds ratio as:
 
:<math>\text{DOR} = \frac{26/3}{12/48} = 34.666\ldots</math>
 
This diagnostic odds ratio is greater than one, so we know that the test is discriminating correctly. We compute the confidence interval for the diagnostic odds ratio of this test as [8.967, 134.0].
 
Now consider another test with ten extra false negatives; its diagnostic odds ratio is:
 
:<math>\text{DOR}^\prime = \frac{26/13}{12/48} = \frac{2}{1/4} = 8</math>
 
This diagnostic odds ratio is also greater than one, but is lower, indicating worse performance, as we would expect if the number of false negatives increased. The confidence interval for the diagnostic odds ratio of this test is [3.193, 20.04]. The confidence intervals for these tests are clearly overlapping, so we would not conclude that the first test was statistically better than the second.
 
== Criticisms ==
The diagnostic odds ratio is undefined when the number of false negatives or false positives is zero. The typical response to such a scenario is to add 0.5 to all cells in the contingency table,<ref name="Glas 2003" /><ref name="Cox 1970">D.R. Cox. The analysis of binary data. Methuen, London, 1970.</ref> although this should not be seen as a correction as it introduces a bias to results.<ref name="Moses 1993">Lincoln E. Moses, David Shapiro. Combining independent studies of a diagnostic test into a summary ROC curve: data-analytic approaches and some additional considerations. Statistics in Medicine, 12(12) 1293&ndash;1316, 1993.</ref> It is suggested that the adjustment is made to all contingency tables, even if there are no cells with zero entries.<ref name="Moses 1993" />
 
== See also ==
* [[Sensitivity and specificity]]
* [[Binary classification]]
* [[Positive predictive value]] and [[negative predictive value]]
* [[Odds ratio]]
 
== References ==
{{reflist|2}}
 
[[Category:Epidemiology]]
[[Category:Biostatistics]]
[[Category:Medical statistics]]
[[Category:Statistical ratios]]
[[Category:Summary statistics for contingency tables]]

Revision as of 03:41, 1 March 2014


As you can see from the above article, it is easy to understand how to make money online when you get the knowledge through great tips. You can join the millions of people worldwide who make money each day, if you como ficar rico pay close attention to the tips that you have just read. Making money online is a skill, and if you continue to study good tips and ideas such as these, there is no reason why you cannot make lots of money online. 


that's a lie. Don't fall prey to these types of websites and always read the reviews before joining. Talking to experts in their field can help you to use como ganhar dinheiro the Internet successfully. Try to network with people who do what you want to do. Doing these things can help give you an advantage over your competition.

If you want to do something creative, consider ways to create viral videos. Brainstorm ideas that you think are rip riotously hilarious, then start putting them into action. Post them on YouTube, turn on ads and, if they work, watch the money start rolling in! Learn about marketing to see how you can get them even more popular. como ficar rico If  ganhar ganhe dinheiro you know how to prepare taxes, you can earn money online. Apply for the necessary government licenses and then begin offering your services online. Many of today's top producers work from home with only their laptop and an email address. For best results, continually advertise your services throughout the year.

Medical transcription can be a good way to make money online as a full time career. Formal training is required, and this can be costly. Additionally, it is necessary to have good computer and transcription equipment that works reliably. A great deal of work is available for people who are able and willing ganhando dinheiro na internet to invest in training and good equipment. Pay is quite substantial. You can sell your wares on the Internet to make money. Certain sites will help you to do your selling. You can personalize the t-shirts for your client. You can advertise by putting fliers up around the neighborhood or by using Craigslist.

Don't buy every book about making money online. Most of the time, these books are sold by people whose claim to fame is that they are teaching people how to make money como ganhar dinheiro online. Before you buy an e-book or book about making money, make sure that you know a little about the author, and that you have seen testimonials about the book.

To really make money online, consider setting up your own site and having all the control. You could sell things as an affiliate or offer professional services, among many other things. While working for others can earn you a nice income, there's nothing like raking in all the profits and calling ganhar dinheiro pela internet all the shots yourself! As stated above, there are lots of ways to increase your online income. Use these suggestions to help you get started. You will be amazed at how quickly the money can add up. Come back to this page and others like it to continue growing your online work portfolio as you go.

Affiliate marketing can be a good way to earn money online if you have a lot of time and energy to spend on website setup and promotion. Affiliate marketers market the products of others in a number of ways. If you are you looking for more information about ganhar dinheiro review comoconseguirdinheiro.comoganhardinheiro101.com You can create a website and promote como ganhar dinheiro na internet it. Creating a blog or posting on the blogs of others in your niche is also an excellent way to share product information. Making smart use of social media and e mail marketing are also possibilities for successful affiliate marketing.

Take advantage of paid per post if you have extra time and need to make money online. People will need you to make posts on their site to promote a product or give a good review, which will help them in the long run. In return, they will pay you a nice sum. Do you enjoy ganhe dinheiro na internet writing? If so, you can make cash by becoming a freelance writer. Just be aware that most freelance writing sites prefer writers with experience. But, there are other sites that will hire you if you pass a test. It's a bonus if you have knowledge on particular subjects.


Manage your time wisely when you are trying to make money online. You may have a real-world job, which means you have to budget time wisely. Set a schedule that will allow you enough time to balance the two. Also make sure that you are being efficient in that time, so you don't run into stress como conseguir dinheiro about working online. Becoming a ghost writer is a great way to earn money online. There are people who need content for their websites, but who lack good writing skills. You can write for them and earn money for what you write. Many people are earning a good income writing for others this way.

Several websites out there pay for people to do tasks that cannot be handled by a computer. It might be flagging inappropriate activity or finding the name of a business on a receipt. These tasks require human intelligence to find the answer. They are reasonably simple to perform and can provide you with some extra como ganhar dinheiro na internet money. Translate documents if you are fluent in a second language and want to make money on the side. Check out the freelancing sites to find people who will need things altered into a different language. This can be anyone from a large corporation to an individual who wants to translate something for a friend.

To really make money online, consider setting up your own site and having all the control. You could sell things as an affiliate or offer professional services, among many other things. While working for others can earn you a nice income, there's nothing like raking in all the profits and calling como ganhar dinheiro all the shots yourself! As stated above, there are lots of ways to increase your online income. Use these suggestions to help you get started. You will be amazed at how quickly the money can add up. Come back to this page and others like it to continue growing your online work portfolio as you go.

Manage your time wisely when you are trying to make money online. You may have a real-world job, which means you have to budget time wisely. Set a schedule that will allow you enough time to balance the two. Also make sure that you are being efficient in that time, so you don't run into stress como conseguir dinheiro about working online. Becoming a ghost writer is a great way to earn money online. There are people who need content for their websites, but who lack good writing skills. You can write for them and earn money for what you write. Many people are earning a good income writing for others this way.

If you want to do something creative, consider ways to create viral videos. Brainstorm ideas that you think are rip riotously hilarious, then start putting them into action. Post them on YouTube, turn on ads and, if they work, watch the money start rolling in! Learn about marketing to see how you can get them even more popular. ganhar dinheiro na internet If you know how to prepare taxes, you can earn money online. Apply for the necessary government licenses and then begin offering your services online. Many of today's top producers work from home with only their laptop and an email address. For best results, continually advertise your services throughout the year.

If you're a performer, YouTube may help you earn income online. Make a brief video clip showcasing your talents. Are you a whiz with cosmetics? Make online tutorials that focus on makeup. Do you view yourself as a comedian? Why not film a brief comedy routine on hot news topics? When your videos have ganhar dinheiro been uploaded to the site, advertisements will be attached to your page and this will lead to payment. There are many ways you can make money online; all you need is some basic information. This article should have helped you get started. Use these tips to earn as much or as little as you need online.

that's a lie. Don't fall prey to these types of websites and always read the reviews before joining. Talking to experts in their field can help you to use ganhar dinheiro na internet the Internet successfully. Try to network with people who do what you want to do. Doing these things can help give you an advantage over your competition.

If you have the ability to type quickly, you may consider transcription jobs. You need to have good headphones and the ability to keep up with what is being said. Often, the companies will have their own formatting guidelines. Familiarize yourself with these prior to beginning. Once you have, you can begin transcribing. What do you do? Do it for pay! A number of websites offer you points when you search through them and/or make purchases of items that you were planning to buy anyway. Take the points you earn and trade them for gift cards, gifts and sometimes even cash. Sites thatprovide this opportunity include Swagbucks and Mypoints.

Retrieved from "https://en.formulasearchengine.com/index.php?title=Sparse_distributed_memory&oldid=269313"