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 Thursday, May 15, 2003 #5974

I can use random probability to calculate reach. Is there any way I can create a complete frquency distribution? For instance, Is it correct to add up probabilities for an individual for 4 publications (Say 0.75, 0.75, 0.5 and 0.25) and say that frequency for the person is 2.25?
 The Media Guru Answers(Sunday, May 18, 2003 ):

The Guru follows neither your math nor your logic here.
If your example means the the indivisual has a 75% chance of reading the first publication, etc how would that give the person a 2.25 frequency for the 4? You are working with almost unrelated data, not to mention the overstatement of random probability in calculating reach of related media. Further, frequency distribution deals with the numbers of persons who experienced each integral frequency, i.e. how many had one exposure, how many had two exposures. No individual may have a fractional exosure.
 Tuesday, April 22, 2003 #5943

i believe there is a rule of thumb when calculating the reach of trade publications. something like the first major pub in the buy gets over like 75 or 80% and then there is a average increase per added pub. It's just a rule of thumb, but it sure would be useful since we cannot define the size of the overall industry's target universe. IF you do not know this rule of thumb, how would you suggest we calculate the reach and frequency of 5 trade pubs bought with differing levels of insertions over a year. Thanks for any help!
 The Media Guru Answers(Saturday, April 26, 2003 ):

Crudely: calculate each book's circulation's percentage of the sum of the goups' circs and make this each one's individual reach. Start with the largest and calculate the added reach contribution of the others by random probability.
 Monday, March 03, 2003 #5863

Dear Guru, I learnt in school using onlyonlyboth method to calculate the reach for media A only, media B only and both. However, if there are more than two media, how to calculate the reach of media A+B+C?
And reach for media C only?....
 The Media Guru Answers(Monday, March 03, 2003 ):

The trick is to look at the percent who do not see each medium. This is 100% minus the percent who DO see A. The percent who do not see medium A times the percent who do not see medium B is the percent who see neither. 100% minus the percent who see neither = net reach of both. Working this way the calculation can be readily chained as far along as needed.
In other words, if you have  Reach of A = 20%
 Reach of B = 24%
 Reach of C = 31%
 Reach of D = 47%,
then the calculation for the net reach of all is
0.8 x 0.76 x 0.69 x 0.53 = 0.22 so net reach = 78%. Remembering that as above, if reach is the probability of seeing a medium, then 100 minus reach is the probability of NOT seeing the medium, you should be able to calculate exclusive reaches as needed.
 Friday, February 07, 2003 #5815

We've been asked to estimate reach/frequency/etc. for a plan that includes USA Today, newspapers in 810 major markets, spot radio in 5 markets, metro traffic in 810 markets, and national magazines. I think this is impossible, but can you think of any way I can provide the client with a decent estimate? I was thinking I could start by pulling delivery for USAT, magazines, New York Times, and then somehow estimating the rest.
 The Media Guru Answers(Saturday, February 08, 2003 ):

The Guru sees no problem, and so does not quit understand your question perhaps. Assuming you know what reach and frequency is, you can readily determine the reach of each one of the media you mention. Most simply, you can combine them by Random probability . Most reach and frequency systems on the market, like our own eTelmar, can do this for you. The only "trick" is accounting for the different geographies, but that's just artithmetic, and easy if you look at all the percentage reaches as their equivalent in thousands.
 Thursday, October 03, 2002 #5543

Considering the amount of versions found on the interpretation that Rating. I want that please you help to clarify me having the concept of rating considering that the form of I calculate is expressed taking the total of minutes seen by target versus the probability of the total of minutes during a time period.
Of this form the rating would be a % of time dedicated by a group I specify in the time certain period?
 The Media Guru Answers(Sunday, October 06, 2002 ):

As used by the Guru, rating is the audience of a single event (program or commerical) compared to the population universe for the defined demographic. Thus, if 1000 people 1849 see a oneminute commercial and the defined market has 100,000 population of persons 1849, the rating is 1.0.
In your example, if persons watch 30 minutes of a 30 minute program, the rating is apparently 100, though your use of the word "probability" is puzzling.
In the Guru's example, the "probability" of a target person seeing a minute of the program is 1%. In your example, you appear to be addressing a totlaly different concept.
 Friday, June 29, 2001 #4538

Hello again,
I have two questions about calculating reach and frequency that I have been unable to find in the archives of past responses. Perhaps you can help?
1. I normally use the formula (a+b)(.a*b) to determine combined reach of two mediums, such as radio and print. How do I calculate the combined reach of more than two? The plan I am working on includes spot TV, spot radio and local newspaper.
2. Is it possible to determine a combined reach for more than one market or should each market be reported separately? In the past, I have provided separate delivery for each market in the same plan with a total number of gross impressions for the whole plan. Is this correct?
Thanks in advance!
 The Media Guru Answers(Friday, June 29, 2001 ):

1. This common formula is based on an assumption that different media duplicate their audiences according to random probability. Therefore if you follow this assumption, media may be added to combinations of media in a "chain" of the same formula. So, once you have combined TV and Radio, you can use this combination as your "a" and then combine it with newspaper as "b."
2. You can combine reaches across markets by doing a weighted average. Multiply the reach in each market by the percent of U.S. in each market. Add all the products and divide by the sum of the % U.S.
 Thursday, March 16, 2000 #3326

Dear Guru:
I would like to know if there is any equation to calculate media mix reach?
 The Media Guru Answers(Thursday, March 16, 2000 ):

There are several, equivalent ways to express the arithmetic to combines media according to random probability, which has been found generally adequate for the purpose of multimedia combination.
Here's an easy one:  Work with two reaches at a time
 Treat the reach of each medium as a decimal (50 reach is 0.5)
 Add reach of medium A and medium B
 Multiply reach of medium A by Reach of medium B
 Subtract the product of the multiplication from the sum of the addition
Example:  Reach of medium A = 40, reach of medium B = 55
 0.4 + 0.55 = 0.95
 0.40 x 0.55 = 0.22
 0.95  0.22 = 0.73
 Combined reach is 73
To add additional media, treat the combination as medium A and the next medium as B.
In some cases, a planner may have access to research which shows that an adjustment should be made for actual, measured, duplication between different media, rather than use the "random probability" formula above. In that case, more sophisticated reach calculating software packages, such as those from
Telmar allow you to make the calculation and build in known adjustments.
 Tuesday, September 14, 1999 #2792

What can you tell me about reachbased planning?
Thank you in advance.
 The Media Guru Answers(Tuesday, September 14, 1999 ):

>
The usual assumption is that print and broadcast duplicate with random probability, there is no special, greater or lesser likelihood that persons in the audience of the print schedule will also be or not be in the audience of the broadcast schedule.
Mechanically. the combination may be calculated in a few equivalent ways. The Guru finds it easiest to consider the reaches as decimals (50% reach = 0.50). Subtract the reach of print from 1 and multiply this by 1minus the reach of broadcast. Suppose print has a 40% reach and broadcast has 55%. By subtracting 0.4 from 1 (1  0.4 = 0.6), you have the probabilty of the target not being exposed to print. Subtract 0.55 from 1 to get the probability of not being exposed to broadcast (1  0.55 = 0.45)
Multiply these two together (0.6 * 0.45 = 0.27) and you have determined there is a 27% probability of people not being exposed to either of the combined media, or a 73% reach.
This formula is typically used in media software to combine different media. Certainly there are cases where there is a somewhat better than random probabilty of media duplication, such as TV Guide combining with a TV schedule, but that's the exception, calling for judgement.
 Friday, April 30, 1999 #2481

Is there any way to calculate duplication across a media plan using several media (e.g. print and radio and TV), or can I only get a duplication analysis within a media (radio duplicaton and then another duplication factor for print, etc , etc)
I use telmar for research with simmons and arbitron access and we also use JDS for buys.
 The Media Guru Answers(Friday, April 30, 1999 ):

The standard assumption in media planning is that duplication between different media is purely at random. Therefore, the random probability formula is used:
 Express the reach of each medium as a decimal (50% reach = 0.5)
 Multiply the reach of one medium by another to determine the duplication.
 Subtract the duplication from the sum of the two reaches to get the net reach
So, if you have a 40% reach in TV and a 55% reach in Print, multiply
0.4 x 0.55 to get 0.22
subtract 0.22 from 0.4+.55 and get 0.73 or 73% reach of the combined media.
There are a variety of ways to do the calculation. The Guru actually prefers to use the probablilty of not seeing each medium (reach as a decimal subtracted from 1.0) When these are multiplied they give the net probability of not seeing any of the media. When this result is subtracted from 1, the final result is net reach. This style is particulary useful for combining several media at once.The example would combine this way:  10.4 = 0.6
 10.55 = 0.45
 0.6 x 0.45 = 0.27
 10.27 = 0.73 or
73% reach.
Telmar's "Media Mix" program uses these assumptions.
 Wednesday, December 02, 1998 #2192

Dear Guru. It is not still clear to me how to
measure or calculate Reach of the ad campaign
using media mix. For example, my ads on TV provided
90% reach, and ads in print reached 25% of the
target audience. What is the total reach, frequency
of the campaign? What other indexes can we find for
such campaign?
And my second question is about outdoor advertising.
It is essential to measure the effectiveness of the
ad campaign comparing awereness and sales before and
after the ads placing. But that is somehow the post
campaign analisys and my client would like to see some
feagures before the campaign starts (precampaign).
What indexes (like reach, frequency, GRPs, OTS) can
we provide to the discription of the outdoor
ad. campaign? Thank You very much.
 The Media Guru Answers(Wednesday, December 02, 1998 ):

Reach of a medium in a plan is simply a statistical probability. Further, it is generally thought that each medium overlaps each other medium randomly.
So, in your example, if you consider the reach of each medium as a decimal, the probability of not being exposed to TV is 0.10 and of not being exposed to print is 0.75.
The probability of not being exposed to either one, is therefore 0.10 times 0.75 = 0.075.
Therefore, total reach of the mix is 92.5 (if 0.075 or 7.5% don't see it then 92.5% do see it).
Other basic "counts" for a campaign are impressions (OTS), cost per rating point and cost per thousand impressions.
All of these counts; reach, frequency, GRP, OTS, etc are possible for outdoor, if the research has been done, in your country, to count the audience of the locations used.
 Tuesday, June 09, 1998 #1886

how do i calculate reach of TV+PRESS, Is there a formula
 The Media Guru Answers(Tuesday, June 09, 1998 ):

As a rule, TV and press are thought to duplicate in a random pattern. That is, the random duplication formula is appropriate. The reach of each medium is treated as a decimal. To calculate net reach, we combine the probabilty of each medium's NOT reaching the target, to get the combined probability of neither reaching the target. The remaining people are the ones reached.
The formula works as follows when TV reach is 45 and press reach is 37.
People not reached by TV would be 0.55 of the target
People not reached by press would be 0.63 of target
Total people NOT reached are 0.55 x 0.63 or 0.35 of target.
The remainder of target is reached (1.0  0.35 = 0.65) so reach is 65
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