For any size data set, the standard deviation is a reliable statistic for reporting precision. There are two formulas for calculating standard deviation, with a very slight difference between them. You will use one formula if your measured data represents an entire population. You will use the second formula if your measured data is from only a sample of the population. Your data represents an entire population if you have collected all the measurements possible from all possible subjects. For example, if you are conducting tests on people with some very rare disease, and you believe that you have tested everyone with that disease, then you have the entire population. The standard deviation formula in this case is: =(x)2n{\displaystyle \sigma ={\sqrt {
rac {\Sigma (x-\mu )^{2}}{n}}}} A sample set is any group of data less than an entire population. This is actually going to be used more often. The standard deviation formula for a sample set is: =(x)2n1{\displaystyle \sigma ={\sqrt {
rac {\Sigma (x-\mu )^{2}}{n-1}}}} Notice that the only difference is in the denominator of the fraction. For an entire population, you will divide by n{\displaystyle n}. For a sample set, you will divide by n1{\displaystyle n-1}. As with calculating the average deviation, you will begin by finding the mean of the data values. Using the same set of measurements as above, the mean is 12.4. For each data point, subtract the data value from the mean, and square that result. Because you are squaring these variations, whether the difference is positive or negative does not matter. The square of the difference will always be positive. For the five data values in this sample, these calculations are as follows: (1212.4)2=(0.4)2=0.16{\displaystyle (12-12.4)^{2}=(-0.4)^{2}=0.16} (1112.4)2=(1.4)2=1.96{\displaystyle (11-12.4)^{2}=(-1.4)^{2}=1.96} (1412.4)2=1.62=2.56{\displaystyle (14-12.4)^{2}=1.6^{2}=2.56} (1312.4)2=0.62=0.36{\displaystyle (13-12.4)^{2}=0.6^{2}=0.36} (1212.4)2=(0.4)2=0.16{\displaystyle (12-12.4)^{2}=(-0.4)^{2}=0.16} The numerator of the standard deviation fraction is the sum of the squared differences between each value and the mean. To find this sum, add together the figures from the previous calculation. For the sample data set, these are: 0.16+1.96+2.56+0.36+0.16=5.2{\displaystyle 0.16+1.96+2.56+0.36+0.16=5.2} This is the one step that will differ for either a population calculation or a sample set calculation. For a full population, you will divide by n{\displaystyle n}, the number of values. For a sample set, you will divide by n1{\displaystyle n-1}. This example has only five measurements and is therefore only a sample set. Thus, for the five values being used, divide by (5-1) or 4. The result is 5.2/4=1.3{\displaystyle 5.2/4=1.3}. At this point, the calculation represents what is called the variance of the data set. The standard deviation is the square root of the variance. Use a calculator to find the square root, and the result is the standard deviation. =1.3=1.14{\displaystyle \sigma ={\sqrt {1.3}}=1.14} Using this calculation, the precision of the scale can be represented by giving the mean, plus or minus the standard deviation. For this data, this will be 12.41.14. The standard deviation is perhaps the most common measurement of precision. Nevertheless, for clarity, it is still a good idea to use a footnote or parentheses to note that the precision value represents the standard deviation.
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One-sentence summary -- Use the correct formula for standard deviation. Find the mean of the data values. Find the square of each variation. Calculate the sum of the squared differences. Divide by the data size. Find the square root of the result. Report your result.

If a tsunami hits, save lives, not possessions. Trying to retrieve things and belongings may hamper your escape by causing you to lose valuable time. Grab your safety pack, something to keep you warm, your family and leave immediately. Tsunami survivors act quickly, and usually, don't bother with trying to save possessions. The first thing you should try to do, if possible, is to move away from the coast, lagoons or other bodies of water, towards higher ground and even into hills or mountains. Move until you are either 2 miles (3.2km) inland or 100 feet (30m) above sea level. Expect roads to be totally wiped out by a tsunami. If you're planning on using roads to get where you need to go, think again. In a full-blown tsunami, many roads will be wiped out, either by the seismic activity of the earthquake or by the tsunami itself. Have a good sense of the general direction you want to be heading in, and consider keeping a compass in your survival pack. If you cannot head inland because you are trapped, head up. A tsunami evacuation tower is a tower designed to withstand a tsunami. The walls of the tower are designed to break away, allowing water to pass through while preventing large debris from toppling the tower. If you cannot find an evacuation tower, then climb a high-rise.Although not ideal because the structure itself could collapse, if this is your only option, choose a high, sturdy and solid building and climb up it. Go as high as you possibly can, even onto the roof. . As a very last resort, if you find yourself trapped and unable to move inland or climb a high building, find a strong and tall tree and climb up it as high as you can. There is a risk of trees being dragged under by the tsunami, however, so this really is a measure to be used only if all other alternatives are impossible. The stronger the tree, the higher it stands, and the sturdier its branches for resting on (you may be there for hours), the better your chances are of surviving. If you did not manage to evacuate but find yourself caught up in the tsunami for one reason or another, there are things that you can do to try to survive: Grab onto something that floats. Use a floating object as a raft to keep yourself above the water. Items that float such as tree trunks, doors, fishing equipment etc. may be in the water with you.
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One-sentence summary -- Abandon belongings. Move inland and to high ground. Climb an evacuation tower. Climb a sturdy tree React quickly if you are caught up in the water.

To get the ultimate look from your at-home gel nails, start with the ultimate blank nail. Take the time to cut, file, and shape your nails. Before you cut them, decide what shape you want. Cut the basic shape and then file the tips. Finally, finish shaping by rounding the surface of your nails with a buffer. You can create round, square, pointy, almond, or oval nails. Because gel nails are based off of your nails, this is when you shape your nails. It is not like applying acrylic nails that can be shaped during/after application.
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One-sentence summary --
File and shape your nails.