If we use too few decimal places, the result will be imprecisely reported. On the other hand, if we use too many decimals, we give the impression that the result is more precise than it really is.
How many decimals to use should be a conscious choice. Using more decimals than necessary is not wrong per se. However, an unnecessarily large number of decimals gives the impression that issues of measurement uncertainty or random variation have not been handled purposefully. Moreover, it conceals the message – the results are swamped by a surfeit of figures.
The height of adults is normally reported in whole centimetres. Bjørnely et al. studied changes in body mass index in adolescents from 1966 to 1997 (1). They reported height in centimetres with one decimal, with a mean of 180.1cm and a standard deviation of 7.0cm for the 499 boys who were 18 years old. Although each individual measurement can be given in whole centimetres, the mean will have greater precision, and in this case it made sense to report it with one decimal place. If one wanted to report a 95% confidence interval for expected height, it would be from 179.5 to 180.7. Note that here we have the same number of decimal places in the mean, the standard deviation and the confidence interval. When we have an absolute scale, this makes sense.
Furthermore, the number of decimal places depends on the measurement scale. If we reported height in metres instead of centimetres, we would need three decimals instead of one. This is quite obvious here, but is not so for all measurement scales.
If we use too few decimal places, the result will be imprecisely reported. On the other hand, if we use too many decimals, we give the impression that the result is more precise than it really is.
For example, some references suggest that in reporting statistics (eg, means and standard deviations [SDs]) not to use precisions higher than the accuracy of the measured data (1); many researchers recommend to use only one decimal place more than the precision used to measure the variable (2,3); and, some mention that ...
We use decimals every day while dealing with money, weight, length etc. Decimal numbers are used in situations where more precision is required than the whole numbers can provide. For example, when we calculate our weight on the weighing machine, we do not always find the weight equal to a whole number on the scale.
We can round decimals to a certain accuracy or number of decimal places. This is used to make calculation easier to do and results easier to understand, when exact values are not too important.
The first decimal place to the right of the decimal point is the tenths place.The second decimal place is the hundredths place.The third decimal place is the thousandths place. The decimal system continues up to the ten-thousandths place, the hundred-thousandths place, the millionths place and beyond.
Decimal places are those to the right of the decimal point, e.g. 5.368 has three decimal places. To round this to two decimal places: find the second decimal place (6) and look at the number to its right (8). As that number is between 5 and 9, the second decimal place is rounded up to the next whole number, which is 7.
Rounding a decimal number to two decimal places is the same as rounding it to the hundredths place, which is the second place to the right of the decimal point. For example, 2.83620364 can be rounded to two decimal places as 2.84, and 0.7035 can be rounded to two decimal places as 0.70.
A fraction is one whole number divided by another (but we can't divide by zero). Every fraction, small or large, positive or negative, can be written as a decimal. For example, 1/2 = 0.5, 1/3 = 0.333… and 1/7 = 0.142857142857… – where the '142857' repeats forever!
The humble decimal point may have been invented about 150 years before we previously thought. Experts had previously credited German mathematician Christopher Clavius for the innovation, but according to a new study, the credit actually belongs to Italian merchant and mathematician Giovanni Bianchini.
America. The countries found to the north, like the U.S.A and Canada, use the decimal point, although the comma is used in the Francophone area of Canada as well. Countries closer to Central America, such as Mexico and the Caribbean Islands, also use the decimal point.
If the digit in the smallest place is less than 5, then the digit is left untouched. Any number of digits after that number becomes zero and this is known as rounding down. If the digit in the smallest place is greater than or equal to 5, then the digit is added with +1.
5 is exactly half-way between 0 and 10, and 8 is between 5 and 10. So 8 is closer to 10 than to 0 on the number line and so it rounds up to 10. 32 lies between 30 and 40. 35 is exactly half-way between 30 and 40, and 32 is between 30 and 35.
Rounding numbers makes them 'easier' to use or understand while also keeping the number close to its original value. Instead of using exact numbers, simpler values can be used. For example, 189.2 could be rounded to 189, 190 or 200, depending on the degree of accuracy required.
Percentages appearing in reference and methodological tables must be rounded to no more than two decimal places except in certain methodological tables where finer breakdowns may be necessary.
A top- loading balance may only give you two decimal places in your mass reading, whereas an analytical balance may give you three or four decimal places. If your sample is more than 10 g, a top-loading balance will give you at least four significant figures.
Introduction: My name is Terence Hammes MD, I am a inexpensive, energetic, jolly, faithful, cheerful, proud, rich person who loves writing and wants to share my knowledge and understanding with you.
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