How to Calculate Relative Risk

Relative risk is a statistical term used to describe the risk of a certain event happening in one group versus another. It is commonly used in epidemiology and evidenced based medicine, where relative risk helps identify the risk of developing a disease after an exposure (i.e. a drug/treatment or an environmental exposure) versus the risk of developing a disease in absence of the exposure. This article will demonstrate how to calculate relative risk.


1. Draw a 2x2 table. A 2x2 table is the basis for many epidemiological calculations.

• Before you can draw a 2x2 table yourself, you must understand the variables:
  • A = The number of people who both had the exposure and developed the disease
  • B = The number of people who had the exposure but did not develop the disease
  • C = The number of people who did not have the exposure but did develop the disease
  • D = The number of people who neither had the exposure nor developed the disease
• Let's do an example 2x2 table.
  • A study looks at 100 smokers and 100 non-smokers, and follows them for development of lung cancer. 

• Right away, we can fill in part of the table. The disease is lung cancer, the exposure is smoking, the total numbers of each group is 100, and the total of all the people in the study is 200.
• At the end of the study, they found that 30 of the smokers and 10 of the non-smokers developed lung cancer. Now we can fill in the rest of the table. 

Since A = the number of people exposed who got the disease (i.e. smokers who got lung cancer), we know this is 30. We can calculate B simply by subtracting A from the total: 100 - 30 = 70. Similarly, C is the number of non-smokers who got lung cancer, which we know is 10, and D = 100 - 10 = 90.

2. Calculate the relative risk using the 2x2 table. The general formula for relative risk, using a 2x2 table, is: 

 

We can calculate relative risk using our example:



Therefore, the relative risk of acquiring lung cancer with smoking is 3.

3. Interpret the results of relative risk.

• If the relative risk = 1, then there is no difference in risk between the two groups.
• If the relative risk is less than 1, then there is less risk in the exposed group relative to the unexposed group.
• If the relative risk is greater than 1 (as in the example), then there is greater risk in the exposed group relative to the unexposed group.

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How to Copy Paste Tab Delimited Text Into Excel

Taking text files and getting them formatted into Excel can be a difficult process. Often, it can be useful to copy-paste from text files into Excel. However, Excel can make this confusing and difficult.



1. Copy-paste a tab delimited text into Excel (likely, this will only show up in the first column).
  
 2. Ensure the column you just pasted is highlighted.
  
3. Open the menu Data-> Text to Columns.

 
4. Select 'Delimited' and click 'Next'. 

 
5. Select 'Tab'. 

 

6. Click 'Finish'.

 

7. Now, you can paste additional tab-delimited text into Excel without needing to apply the Text to Columns function. Instead, they paste into the appropriate   

 
8. Finished. 

How to Mark Your Direct Messages As Read on Twitter

Direct messages on Twitter can be sometimes very annoying if you get many of them. Marking them all as read at once can be a good way of removing them from your view without having to sift through each one.

1. Sign in to your Twitter account. Type in your username and password.

 

 

2. Click on the gear icon. You can find it on the top right of your homepage, to the right of your search bar. 

3. Select "Direct Messages." It's the first option from the top of the drop-down menu. A new window will pop up.

  

 

Alternatively, you can click on 'Me' and press the messages icon.

4. Click on the 'tick' icon. This means that you want to mark the direct messages as 'read'.
 

5. Once you do click on it, click on 'Mark all as read'.

How to Take a Screenshot in Mac OS X

If you need to snap a picture of a funny chat conversation, show an expert an error message on your system, create instructions for performing a task, or even contribute to a wikiHow article, a screenshot is the ideal way to show someone exactly what is on your computer screen. Taking a screenshot on Mac OS X is easy, and there are a variety of simple ways to capture just the image you need.



1. Press Command+Shift+4. Your cursor will turn into a small cross-hair reticle.

2. Click and drag your cursor to highlight the area you'd like to take a picture of. A grayed rectangle should appear where you drag your cursor. If you need to adjust your windows at all, press esc to return to a regular cursor without taking a picture.

3. Let go of the mouse. You should hear a brief camera shutter noise if your computer's sound is turned on. That signals that your screenshot has been taken.

4. Find your screenshot on your desktop. It will be saved as a .png file named "screenshot" labeled with the date and time. Earlier versions of OS X will save it as "Picture #"—for example, if it's the 5th screenshot on your desktop it will be labeled "Picture 5".


5. Use the screenshot. Once you have taken your screenshots, they are ready to be used as you need. You can attach them to an email, upload them to the Web, or even drag them straight into an application such as a word processor.

Antonio Di Natale has no intention of leaving Udinese for Juventus

Antonio Di Natale is committed to Udinese "for life" after shrugging off renewed interest from Serie A champions Juventus.

The 35-year-old striker has scored 158 league goals in a prolific nine-year spell with Udinese, hitting the target 23 times last season to finish six goals behind top scorer Edinson Cavani of Napoli.

His final-day strike in a 5-2 victory at Inter Milan confirmed his side's qualification for the Europa League for another year.

Juve are eager to strengthen their forward line and, having already secured Spanish striker Fernando Llorente from Athletic Bilbao, the Bianconeri are reportedly preparing a fresh approach for Di Natale.

Di Natale rejected a move to Turin in 2010 and the chance to further establish himself as an icon in Udine means the answer will remain the same this summer.

"I think that what I've done with Udinese will go down in the history of the club," he told fifa.com. "I don't see that as something insignificant.

"The truth is that I've found my natural home in Friuli and I've never thought about leaving a team, a town and a family - the Pozzos [Giampaolo Pozzo is Udinese's president] - who have adopted me like a son.

"I miss Naples and I'm proud to be Neapolitan, but Udine is like a second home for me. I'm feeling great here and I feel the love from the fans. When Juventus contacted me, I told their president [Andrea Agnelli] that I wanted to stay here. That's how we decided that I'd stay here for life.

"There isn't too much pressure here. You can lose a few games and still be able to work in peace. The results speak for that approach. Everyone does their job well - the players, the coach and the club."

Napoli tried to sign Roma duo Erik Lamela and Marquinhos, says president

Napoli president Aurelio De Laurentiis has revealed how he tried to bring Roma duo Erik Lamela and Marquinhos to the Serie A side.

Striker Lamela scored 15 goals in 33 games last season, while teenage centre-half Marquinhos has attracted interest from Spanish giants Barcelona and Real Madrid.

Roma are part-owned by Italian bank Unicredit and De Laurentiis says he went straight to them to enquire about the highly-rated pair.

"I contacted Unicredit directly for Lamela and Marquinhos. I offered them 40million euros (£34.1m)," he told Football Italia.

"Instead, they offered me the services of Pablo Daniel Osvaldo at all costs, but seeing as we have Edinson Cavani right now, we don't need him.

"However, at this moment in time, I'm no longer convinced by Lamela and Marquinhos. I've noted that there are other strong players around who are cheaper."

Edinson Cavani open to playing for Chelsea boss Jose Mourinho

Napoli striker Edinson Cavani has told Sky Sports it would be a pleasure to play under Jose Mourinho at Chelsea.

Cavani, who scored against the Blues for Napoli in the UEFA Champions League last year, reportedly has a £53m buy-out clause, but that hasn't stopped him from being linked with Chelsea, Manchester City and Paris St-Germain.

The Uruguay international is currently preparing for the Confederations Cup in Brazil, where he discussed his future.

When asked about the interest of Chelsea and Manchester City, he said: "I don't know if they made an offer for me, I just know that to be coached by someone like Manuel Pellegrini or Jose Mourinho would always be a pleasure.

"And when the time is right it would be great to play for one of these teams, because when I was a child I imagined doing it - but now I am only thinking about Uruguay. In my career I have always had to deal with rumours of me signing for another team and I just have to keep my feet on the ground."

Cavani also talked about working with new Napoli manager Rafa Benitez.

"I don't know, I think there are other factors that could change my future. I have a contract with Napoli but on the other hand there are some conversations but everything is uncertain at the moment," he continued.

"What I know is that I belong to Napoli, that I'm thinking about my national team because we have a very difficult qualifying game and we also have a difficult tournament [Confederations Cup] to deal with and after all these commitments I'll think about what is going to happen."

Cavani was also asked about his international team-mate Luis Suarez, who is looking to quit Liverpool and the Premier League.

"It depends on many things. I think that English football fits him very well because it is the kind of play that he likes but at the end it is about a personal decision," he said.

He also defended Suarez, who is currently banned in England for biting Chelsea's Branislav Ivanovic.

"These things happen in life when you are on the pitch you are really excited and you have to deal with some situations you are not used to," he said.

"It's not fair to judge a person for one thing on the pitch when there is a match going on and you are extra excited and sometimes you make a mistake.

"The most important thing is that he has recognised he has made a mistake.

"He is the only person who knows where he will play, I don't know what my future will be so I can only guess about another people."