PayScale often receives questions about how many salary survey employee profiles we have.

Our answer is we have enough, and the number is growing rapidly. :-)

This begs the question, how large a salary survey data set is enough? How many data points are required for PayScale data to be truly significant? The number needed depends on what questions are being asked. In this post, I'll look at the questions the United States Bureau of Labor Statistics and PayScale typically ask, and the amount of data each needs to handle statistical fluctuations.

You can experience our data techniques first-hand by trying the PayScale salary survey.

We all know that TV Stars, from Jerry Seinfeld to Ray Romano, pull in very large career salaries, but did you ever wonder what their characters make salary-wise?

Remember the Baywatch cast? Back in their glory days, Pamela Anderson was raking in a reported seven-figure salary, but how much was her character, lifeguard "C.J." Parker, making? They never actually said on any Baywatch episodes, but in California, the hourly wage for a lifeguard, with 5-9 years of experience, is $11.25. If the Baywatch babe was a high-paid lifeguard, she might have been making an hourly wage of $13.60. Kinda makes you wonder how C.J. could afford her cool beach house?   Hmm, they never explained that in any of the Baywatch episodes either.

How does your salary stack up (pardon the pun) against C.J.’s? Do you make more than a Baywatch babe? Find out with our salary calculator.

Controversial wage proposals called "living wage laws" are popping up all over America these days. Earlier this year, the Chicago City Council passed a living wage law aimed at big-box retailers, which would have required stores such as Wal-Mart and Target to pay wages of at least $10 an hour plus $3 in fringe benefits by the middle of 2010.

Wal-Mart and other mega-retailers objected and Chicago Mayor Richard Daley subsequently exercised his first veto in 17 years, vetoing the living wage measure. Mayor Daley said the measure would have unfairly kept big-box retailers out of predominately black city neighborhoods, which need jobs.

How much more is $10 an hour vs. the current minimum wage? In Illinois, the minimum wage is $6.50 an hour, so $10/hour would have been more than a 50% raise, and is almost double the federal minimum wge of $5.15. Beyond the legal minimum, are you being paid the average wage for your job? Find out with our salary calculator.

You might be surprised to learn which jobs can pay a minimum wage, or just a little above.

Would you like to make six figures? Who wouldn’t? Well, it may surprise you to learn that not everyone has to get a medical degree, work as a broker on Wall Street or spend their days inside a law firm to earn in the $100,000 annual salary range. According to Forbes.com, there are some jobs with six figure salaries that do not require an advanced degree.

Can you knock out 200 words per minute? Then you could be one of the 50 to 60,000 court reporters working today. According to Forbes.com, the national average salary is $62,000, but some court reporters can reportedly earn an annual salary of $100,000 in “many cities.” We’d have to assume that includes working overtime, which could be tough on the fingers!

In our ever-crowding justice system, the job outlook for court reporters looks good. However, for those tiring of the legal profession, career changes for court reporters (or other fast typists) include broadcast captioning and real-time reporting for web casts. Are your fingers being paid what they're worth? Find out by typing your job into the PayScale salary survey.

Recently the National Labor Relations Board issued a ruling (3-to-2) that will re-classify registered nurses — and possibly 8 million other workers — as “supervisors” if they perform certain types of duties. The National Labor Relations Board ruled that a worker would be a supervisor if he or she: exercised “independent judgment,” oversaw another worker, could be held accountable for another worker’s performance or spent 10 to 15 percent of total work time in supervisor-type duties.

How will this affect the average nurse salary? In the nursing world, that would mean that a nurse overseeing a shift (the charge nurse) would be considered a “supervisor” if she assigns another nurse to a patient. Ultimately, workers that are re-classified as “supervisors” are excluded from union membership, which will likely affect their pay rate.

According to our salary calculator, a (non-union) registered nurse in Michigan makes an average salary of $45,438. Is a non-union nurse salary significantly different from a nurse with union membership?

It was great to see a blog post on TechCrunch about PayScale. Even better were the comments: they reminded me of questions we regularly get about the effectiveness of our salary survey.

One common question about our salary survey is some variation of, "My job title is software developer. How does PayScale take into account what I actually do?" Software developer can mean everything from writing Excel macros to automating a spreadsheet (I've been doing too much of that lately), to re-writing the Windows NT kernel for 64 bit computing.

How does PayScale handle this variation of duties and job titles?

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-- Started, but couldn't finish before bed-time...
--  Adam
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Have you ever wondered how much a president makes? Over dinner, someone recently asked me how much I thought The President of the US made.  I had no idea, so I referred to my old friend: Wikipedia.  There I learned that the President's salary is $400,000 per year. Then I started wondering how much other types of presidents made.

It might surprise most Americans to learn that there are over 25,000 private contractors in Iraq. These contractors make up the third largest international force in the war-torn country, behind U.S. military and U.K. troops. For this reason, private contractors are often called the “shadow army in Iraq .”

Many jobs that were traditionally performed by the U.S. military - truck driving, security, laundry and food services - have been farmed out to private contractors. The idea is if these military jobs are “outsourced” to contractors, then the U.S. military is freed up for armed conflict.

According to our PayScale salary survey, the average wages for truck drivers in Illinois are around $45,000. If that same trucker works for a private contractor in Iraq, he will reportedly have a starting salary range of $100,000, but are the dangers worth it?

In a previous post, we saw how time consuming it is to calculate with pencil and paper the median salary, or any median of a data set of more than a few data points.

Even after computers became common in the 1950's, and could start doing the work, the mean still was used, because of one further nasty property of medians. Medians require retaining information about every value until the end of the period for which a median is calculated. It you want to know the median salary, you need to save every employee's salary.

Means do not require nearly as much information. In the early days of computers, storing information was expensive, so the mean was still favored for "typical".

A whopping two-thirds of Americans are living paycheck to paycheck, according to the results of the American Payroll Association (APA) 2006 "Getting Paid in America" online salary survey. While the survey probably has a biased sample - who completes a survey by a national association of check processors? - it appears that, for most, their average salary is barely meeting their needs.

On top of the paycheck to paycheck salary statistics, an astounding 81% percent polled in the APA salary survey say that their yearly raises do not cover the increased cost of living. Ouch: inflation is at a historical low. How ugly is this going to get if inflation continues to increase?

Sounds like people cannot afford to be underpaid, and everyone should see if they are, by using the PayScale salary survey.

In the last post, I looked at how hard it was to calculate the median vs. the arithmetic mean ("average") to understand why we ever got in the mess of using mean salary to identify a typical annual salary. To make things simple, I used the example of counting checks and check sizes.

Even for the small data set of 7 days and 15 checks, calculating the median number of checks per day and dollars per check was starting to get laborious. What if you were interested in these numbers for a whole year? How much harder is it to calculate medians vs. means for 365 days and ~750 checks?

In a previous post, I showed how the mean salary and median salary can be very different.

The median is much better than the arithmetic mean for giving a “typical" annual salary; median is the method that we favor in our PayScale salary survey. In fact, the median is better for characterizing “typical” in almost any data set. So then why and how did the mean become the standard for “average” or “typical?”

A Mean Mistake

A historical accident caused the mean to be used for typical or average. Before the first personal computers were introduced, it was much easier to calculate the mean than the median. Scientists in the 1800's, when statistics was being developed, like today, were lazy (I speak from experience). Hence they settled on the easier, but less accurate, way of computing typical values.