Math Tools for Journalists, Chapters 1-4

By Hannah Benson

Despite the fact that a lot of people don’t realize it, journalists deal with numbers every day in the work that they do. When doing reporting work, a journalist must pay close attention to numbers, be it statistics, percentages, numerals, etc.

Chapter 1: The Language of Numbers

This chapter discusses how precise numbers are, and how, due to this, journalists need to know how to capable of understanding the different types of numbers, and how such forms of can get information across. Additionally, journalists need to know how to utilize words to explain numbers and numerical values.

If you open the front page of the newspaper, you’ll see numbers everywhere you look – statistics about a falling stock, the score of the most recent game, the weather for the upcoming week, the amount of cars involved in a crash, etc. Numbers are an essential part of communication in the modern day, and journalism would be incomplete without them. The ability to use these numbers seamlessly and professionally is the mark of a strong reporter.

As a reporter, one needs to be able to check the math of speakers, budgets and official reports. You should never assume that the person who wrote up any report or document has proficient math skills. You should “interview the numbers that same way you interview people:” which means to do so with care. Make sure you consider its form: the impact or meaning, and how easily average citizens will be able to comprehend the topic of such numbers.

A numeral is a symbol which represents a number in either Arabic or Roman forms. Arabic numbers include digits 1-9.

Roman numerals are used for formal titles, to designate historical events and for contraction dates.

One=I   Four=IV   Five=V  Six=VI  Nine=IX  Ten=X  50=L  100=C  5oo=D  1,000=M

Style Tips

  1. Be sure to spell out single digit numbers (one, five, eight).
  2. Utilize numerals for multiple digit numbers (53, 649, 1.3 billion).
  3. Round off larger numbers unless a very specific number is required.
  4. Round off numbers to one decimal point whenever possible.
  5. Spell out fractions that equate to less than one (one-quarter, two-thirds).
  6. When a number is used to assign a position or order in ranking, use words if the number is between first and ninth, but superscript if it equates to 10 or above.
  7. If a number starts a sentence, it needs to be written out in word form, unless it’s a date.
  8. If corporations use numbers in their name, follow their corporate style for writing the number they use.
  9. Numerals are always used for addresses, dates, highways, percentages, speeds, temperatures, times, weights, ages under 10 and money.
  10. You should try and limit the amount of numbers in each paragraph to no more than two or three and only one in a lead for clarity purposes.
  11. Do the math for your readers, you should not expect them to calculate a percentage increase or change over time.
  12. Interpret the results in terms that the readers can understand by using analogies, storytelling techniques or graphics.
  13. Use the word “minus” instead of a dash or hyphen, again, for clarity.
  14. Write out numbers that are used in slang expressions (“thanks a million”).
  15. In a series, use basic style rules, regardless of single or multiple digit numbers.

Language Tips

  1. Use “among” to refer to the group or collective, and “between” for specific, distinct, individual items.
  2. Use “compared to” to compare two items to each other, and “compared with” to examine two items and their statistical similarities or differences.
  3. Use “different from” instead of “different than.”
  4. Use “differ from” when two items are dissimilar and “differ with” when two items are in conflict.
  5. Use “farther” for physical distance and “further” for degree, time or quantity.
  6. Use “fewer” for items that can be counted and “less than” for mass or time terms.
  7. Avoid using the word “fold” when referring to percentages and times.
  8. “Under” is used to refer to a physical relationship, and “less than” refers to a smaller quality or relationship.
  9. “More” means great in quantity and “most” refers to the greatest in quantity. You cannot use “most” in place of “almost.”
  10. “Over” is used to refer to spatial relationships, and use “more than” for figures and amounts.
  11. Use “person” to refer to one individual and “people” for more than one individual.
  12. Use percentages with sentences that have “more” or “less” or end in “-er.”
  13. Describe temperatures as “higher” or “lower,” and not “warmer” or “colder.”
  14. The word “times” is a multiplier and should be used in place of “as much as” format. Do not write “times less,” to show a decrease you should use percentages.

Number translation: Good journalists are able to translate numerical data and language into words and phrases that the average reader can comprehend. Use analogies and amounts in your work that they can understand.

Chapter 2: Percentages

When reporters are writing a story that deals with numbers, often it would be easier and more efficient to simply explain with percentages.

Percentage increase/decrease= Math tools forof literacy.png(new figure – old figure) divided by old figure.

For percentage decrease your numerical answer will be negative.

Salary increases:

  • original x percent increase = $ increase for first year
  • original + salary increase above = salary for first year of contract
  • first year salary x percent increase = $ of salary increase for second year
  • first year salary + salary increase = salary for second year

Percentage as a whole = subgroup divided by whole group

Move the decimal point two places to the right. By calculating the percentage whole, you are able to put the amount into perspective.

Percentage points: May be one one-hundreth of something or other than one.

  • Ex: 7.4% -5.6% = 1.8 percentage point

Simple/annual interest = principal x rate (decimal) x time (years)

  • Principal: the amount of money borrowed
  • Interest: the money paid for use of money
  • Rate: the percentage charged for the use of money

The amount of interest charged depends on the length of time the borrowed money is kept. Most interest rates are calculated based on one year.

Compounding interest (A) = [P x (1 +R)^N x R] divided [(1+R)^N-1]

  • A= monthly payment
  • P= original loan amount
  • R= interest rate, as a decimal and divided by 12
  • N= total number of months

Compounding refers to the interest that is added to the original principal. Loans are compounded more than once a year, such as monthly.

Consumers often make monthly payments on loans, such as home mortgages and car loans.

Interest on savings (B) = P (1+ [ divided by T])^T

  • B= balance after one year
  • P= principal
  • R= interest rate
  • T= number of times per year the interest is compounded

Savings accounts and certificates of deposit generally pay compound interest.

Chapter 3: Statistics

Statistics are often found in crime rates, average costs, student test scores, among others. Journalists are often asked to evaluate surveys and studies, to report accurately on how the numbers are calculated. Journalists need to be aware of potential manipulations of statistics and be able to report on them as a way to seek the truth for the readers.

  • Mean: sum of all figures in a group and divided by total number of figures (average)
  • Median: midpoint in the group of numbers (or add middle two and divide in half)
  • Mode: number that appears most frequently

Percentile: number that represents the percentage of scores that fall at or below designated score. This score is based on its relationship to all the other scores.

  • Percentile rank= number of people at or below score divided by amount of test takers
  • Number of people at or below score= percentile x amount of test takers

Standard deviation: it indicates how much a group of figures varied from the norm. If it is small, it tends to cluster around the mean; this will yield an valid experiment while a high standard deviation will end in inconsistent results.

Such statistical data is often viewed in the form of a bell curve, where the middle represents the mean; the steeper the curve, the smaller the standard deviation is. Standard deviation is measured in terms of the original values (points, dollars, et cetera).

  1. Subtract the mean from each score in the distribution
  2. Square the resting number for each score
  3. Compute the mean for these numbers calculated (variance)
  4. Find the square root of the variance

Probability: examples are lottery, traffic accidents and fatal illnesses

Deaths per 100,000 people = (total deaths divided by total population) x 100,000

The language of risk

  • Have the findings ever been published in peer-review journal?
  • Have researchers established a track record or a reputable organization?
  • What are the researcher’s affiliations?
  • What do other professionals think of the methods?
  • Are the findings preliminary or inconclusive?
  • Do these findings differ from previous studies?
  • Do the findings appear to contradict with mainstream scientific opinion?
  • Are there small or unrepresentative samples?
  • Do conclusions generalize humans from animal studies?
  • Have you only found a statistical correlation?
  • Has risk been expressed in absolute and relative terms?
  • Can risk be compared to anything else?
  • Will the report cause undue anxiety or optimism among readers?
  • Are important caveats included prominently?
  • What do specialist journalists think?
  • Is the headline a fair reflection?
  • What do other professionals in the field think of the research done?

Lottery=pure chance

Coin toss: odds of a series of events= odds of first event x odds of second x odds of third…

  • O: odds
  • N: number of events
  • O^N: odds of a series when each is the same

Chapter 4: Federal Statistics

This chapter looks at unemployment rate, inflation and the Consumer Price Index, gross domestic product and international trade balance, being utilized to make sense of crucial government documents and research.

  • Bureau of Labor Statistics
  • Bureau of Economic Analysis

Labor force: everyone over the age of 16 who has a job or has looked for one in the past month, except those unemployed who haven’t sought work or those institutionalized.

Unemployment rate = (unemployed divided by labor force) x 100

Unemployment: Rate defined as the percentage of the labor force of those unemployed and actively seeking work.


Monthly Inflation Rate=(Current CPI-Prior Month CPI)divided by Prior Month CPI x 100

Inflation: measured by the Consumer Price Index (CPI), shows the amount of inflation in any given month for eight major product groups, such as food and beverages, housing, apparel, transportation and recreation. The CPI notes the prices of items that have been precisely defined from an earlier visit.

Index number: CPI can be reported as an index number, any number greater than 100.

Annual inflation rate (A) = (B-C) divide by C x 100

  • A: Annual Inflation Rate
  • B: Current month CPI
  • C: CPI from same month in the previous year

What is “adjusting for inflation?”

  • This refers to a historical figure that was changed to reflect how large the amount would be in current dollars.

A (adjust for inflation) = (B divided by BC) x AC

  • A: Target year value, in $
  • B: Starting year value, in $
  • AC: Target year CPI
  • BC: Starting year CPI

C (future costs with same annual rate) = K (1 + [I divided by 12])^12

  • C: Cost after one year
  • K: Original cost
  • I: Inflation rate

Gross Domestic Product: The GDP is the value of goods and services produced by a nation’s economy. It is reported quarterly and the rate of GDP growth is reported annually.

GDP = C + I+ G + NX

  • C: consumer spending on goods and services
  • I: investment spending
  • G: government spending
  • NX: net exports (exports – imports)

Trade balance = exports -imports

Trade balance: The difference between the goods and services a country exports to foreign countries and those it imports. For the U.S., this number as long been negative, as Americans are importing more goods than they are exporting. Categories include capital goods not including autos, services which included travel and private services, industrial supplies, autos and auto parts, consumer goods, food and beverages and an other category.



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