General number use

            The use of numbers is important.  The precision and accuracy of numbers lends itself to getting an accurate point across.  That is, if you don’t have any numbers, you are not being as accurate as you can be.  Here are a few lesser known style tips for using numbers correctly:

            First, round off numbers unless a specific number is necessary.  Death counts and budget proposals often need specific numbers, but the amount of flour that Hardee’s uses on a daily basis does need to be as specific.  This rounding will make the piece easier to read.  Secondly, if a number is one digit or seven or more digits, spell it out.  If in between, use the numeral. Spell out fractions.  Don’t use any more than two to three numbers per paragraph.  This makes your writing dense, complex, and unreadable.  Relate a number ot something that the reader can comprehend. For example, saying that the Challenger was going Mach 18 means to the general reader that it was going very fast, but that is it.  If the writer says that the Challenger would have crossed the United States in 12 minutes, then there is a little bit more perspective for the reader.  Avoid using “fold,” as in “it increased three-fold.”  Saying something multiplied three-fold means three times added onto it, so it is technically the original number multiplied by four.  This is confusing for the reader.  The same thing goes with the phrase “three times more than.”  In order to avoid confusion, just say “three times as much.”

 

Percentages

 

            The formula for percentage increase/decrease = (new figure – old figure) / old figure.  Multiply this number by 100 to get a percentage.  If it is a decrease, the result will be a negative percent.  To get the percentage of a whole, divide the subgroup by the whole group (subgroup / whole group) and multiply that by 100.  In order to calculate a batting average for a baseball player, subtract the number of times the player was walked, how many times he sacrificed himself and how many times he was hit by pitches from his total number of at-bats.  Now divide the number of hits that the batter got by this number you have just calculated.

            It is important to differentiate between percentage and percentage points.  For example, if the original number is 10 percent and the new number is seven percent, the number did not drop three percent.  It dropped three percentage points.  The number actually dropped 30 percent from where it started.  In order to calculate interest, one must take the principal (or the amount of money borrowed), multiply that by the rate in decimal form, and then multiply that by time in years.  Payments on compounding interest loans are more complicated, and can be determined with the following formula:

 

A = [P x (1 + R)N x R] / [(1 + R) N - 1] where A is the monthly payment, P is the original loan amount, R is the interest rate in decimal form and divided by 12, and N is the total number of months.

 

Another form of compounding interest comes in checking accounts on banks.  In order to calculate how much interest a person is getting from the bank, use this formula:

 

B = P(1 + [R / T])T  where B is the balance, P is the principal, R is the interest rate, T is the number of times per year that the interest compounds.

1. Ryan took out a loan to pay for his college tuition.  If his original loan of $60,000 had an interest rate of 5.5 percent paid over a course of 10 years, what would be Ryan’s monthly payment?

2. If Ryan had $45,000 in a checking account that had an interest rate of 2.5 percent that is compounded monthly.  How much will Ryan have at the end of the year?

Statistics

The mean, or the average, of a set of numbers is the most common use of statistics.  In order to find the mean of a set of numbers, add the numbers and divide that sum by how many numbers there are in the set.  For example, 2 and 7 equal 9, divide that number by two and the mean is 4.5.  The median of a number set is the number in the middle of the set if the numbers are arranged in numerical order.  The mode of a number set is the number that appears the highest number of times.

Percentiles, often used in standardized testing scores, indicate the performance based on the performance of others.  For example, if a student scores in the 78th percentile on her SAT’s, she knows that she scored higher or equal to 78 percent of the people who took the test.  Or, if 100 people took the test, she would score better or equal to 78 of them.  Computing a percentile is similar to a percent.  Take the number of people at or below the individual score and divide that by the number of test takers to get the overall percentile of the test taker.

Standard deviations are important pieces of knowledge for readers.  The deviation from the mean shows how far above or below the average a number set falls.  If a number set is less standard deviations from the mean, it shows more consistently average performance.  High deviation from the mean means more dynamic performances, for the worse and for the better.

Probability is another important tool for journalists.   Using the exact probability ratio for things like winning the lottery or being struck by lightning are miniscule, often seven or eight decimal places long.  So, the tactic most commonly employed by journalists is to show how many out of 100,000 people it would involve.  So, to calculate the deaths per 100,000 people, one would divide the total number of deaths by the total population and multiply that number by 100,000.

3. If 376,000 students took the SAT’s annually, and Ryan scored higher than 298,000 of them, in what percentile would Ryan’s SAT score rank?

Federal Statistics

            Current unemployment and Consumer Price Index (CPI) numbers can be found on the website of the Bureau of Labor Statistics, www.bls.gov, and GDP and trade balance figures are found on the site of the Bureau of Economic Analysis, www.bea.gov. 

 

            In order to understand the unemployment rate, one must first understand who is in the labor force.  The labor force is defined by everyone over the age of 16 who has a job or has looked for a job in the past month, and is not institutionalized.  Being “employed” means that the person did some sort of work for pay, even one hour, in the week before the survey was taken.  Taking these conditions into account, the unemployment numbers are calculated by taking the number of those unemployed and dividing that number by the total workforce, and then multiplying by 100.

In order to compute the monthly inflation rate use this formula: Monthly inflation rate = (Current CPI – Prior month’s CPI) / Prior month’s CPI x 100.  For annual inflation use the same formula, but instead of “prior month’s CPI,” use the same month from last year.  In order to “adjust your numbers for inflation,” use the following formula: A = (B / BC) x AC, where A is the target year value, B is the starting year value, AC is the target year CPI and BC is the starting year CPI.  Or to figure out how much an item would cost a year from now, use this formula: C = K(1 + [I / 12])12 where C = cost after one year, K is the original cost, and I is the inflation rate in decimal form.

4. If an item costs $45,000 this year and the inflation rate is 2.5%, how much will it cost next year?