Sample Size Calculator Terms: Confidence Interval & Confidence Level The confidence interval (also called margin of error) is the plus-or-minus figure usually reported in newspaper or television opinion poll results. For example, if you use a confidence interval of 4 and 47% percent of your sample picks an answer you can be "sure" that if you had asked the question of the entire relevant population between 43% (47-4) and 51% (47+4) would have picked that answer. The confidence level tells you how sure you can be. It is expressed as a percentage and represents how often the true percentage of the population who would pick an answer lies within the confidence interval. The 95% confidence level means you can be 95% certain; the 99% confidence level means you can be 99% certain. Most researchers use the 95% confidence level. When you put the confidence level and the confidence interval together, you can say that you are 95% sure that the true percentage of the population is between 43% and 51%. The wider the confidence interval you are willing to accept, the more certain you can be that the whole population answers would be within that range. For example, if you asked a sample of 1000 people in a city which brand of cola they preferred, and 60% said Brand A, you can be very certain that between 40 and 80% of all the people in the city actually do prefer that brand, but you cannot be so sure that between 59 and 61% of the people in the city prefer the brand. Factors that Affect Confidence Intervals

There are three factors that determine the size of the confidence interval for a given confidence level: * Sample size
* Percentage
* Population size
Sample Size
The larger your sample size, the more sure you can be that their answers truly reflect the population. This indicates that for a given confidence level, the larger your sample size, the smaller your confidence interval. However, the relationship is not linear (i.e., doubling the sample size does...

...provide advice for consumers, such as doctors, lawyers, government agencies, travel agencies.
The Consumer Buying –Decision Process And The Factors That Influence It.
It should be mentioned that advanced technology provides the opportunity to reduce the costs of searching for information. This makes it easier for customers to make informed decisions.
Social and group forces influence the customer buying –decision process
The social influences affecting consumers’ purchase decisions include culture, subculture, social class, reference groups, and family.
Culture is the set of beliefs, attitudes, and behaviour patterns shared by members of a society and transmitted from one generation to the next. Cultures do change over time. Marketing managers must be alert this changes so that they can adjust their planning to follow it. For example, in some cases, time has become as valuable as money. Australian consumers increasingly require time - saving services (such as fast food) and labour -saving products (such as frozen dinners).
Reference groups: includes a variety of groups that affect consumer behaviours through normative compliance. It should be mentioned that the family is a reference group.
Social class: is a ranking within a society determined by the members of the society. Miller et al (2000) argue that people’s buying behaviour is often strongly influenced by the class they belong to. Such as the upper class, they usually like to buy...

... | Program Evaluation | Sampling | Israel, Glenn D
Determining Sample Size1
Glenn D. Israel2
Perhaps the most frequently asked question concerning sampling is, "What sizesample do I need?" The answer to this question is influenced by a number of factors, including the purpose of the study, population size, the risk of selecting a "bad" sample, and the allowable sampling error. Interested readers may obtain a more detailed discussion of the purpose of the study and population size in Sampling The Evidence Of Extension Program Impact, PEOD-5 (Israel, 1992). This paper reviews criteria for specifying a samplesize and presents several strategies for determining the samplesize.
SAMPLESIZE CRITERIA
In addition to the purpose of the study and population size, three criteria usually will need to be specified to determine the appropriate samplesize: the level of precision, the level of confidence or risk, and the degree of variability in the attributes being measured (Miaoulis and Michener, 1976). Each of these is reviewed below.
The Level Of Precision
The level of precision, sometimes called sampling error, is the range in which the true value of the population is estimated to be. This range is often expressed in percentage points, (e.g., ±5 percent), in...

...Transportation Survey Sample Calculation
The confidence interval (also called margin of error) is the plus-or-minus figure usually reported in newspaper or television opinion poll results. For example, if you use a confidence interval of 4 and 47% percent of your sample picks an answer you can be "sure" that if you had asked the question of the entire relevant population between 43% (47-4) and 51% (47+4) would have picked that answer.
The confidence level tells you how sure you can be. It is expressed as a percentage and represents how often the true percentage of the population who would pick an answer lies within the confidence interval. The 95% confidence level means you can be 95% certain; the 99% confidence level means you can be 99% certain. Most researchers use the 95% confidence level.
When you put the confidence level and the confidence interval together, you can say that you are 95% sure that the true percentage of the population is between 43% and 51%. The wider the confidence interval you are willing to accept, the more certain you can be that the whole population answers would be within that range.
For example, if you asked a sample of 1000 people in a city which brand of cola they preferred, and 60% said Brand A, you can be very certain that between 40 and 80% of all the people in the city actually do prefer that brand, but you cannot be so sure that between 59 and 61% of the people in the city prefer the brand....

...Calculating SampleSize
Types of Samples
Subjective or Convenience Sample
- Has some possibility of bias
- Cannot usually say it is representative
- Selection made by ease of collection
Simple Random Sample
- No subjective bias
- Equal chance of selection; e.g., select the fifth chart seen on every third day
- Can usually be backed to say it is representative
Systematic Sample
- Is a random sample
- Equal chance of selection due to methodology; e.g., computer-generated list of
random numbers, or every fifth name on a generated list
- Can usually be backed to say it is representative
Stratified Sample
- Breakdown the population into subgroups, then take a random sample from each subset
- Can usually be backed to say it is representative
SampleSize Calculation
The Automated Method
If you know your population size and desired confidence level you may use this Web-based calculator to automatically calculate samplesize.
The Manual Calculation Method
To perform samplesize calculation manually, you need the following values:
Population Value: Size of the population from which the sample will be selected. (Number of users or number of encounters)
Expected Frequency of the Factor...

...3) n = 186, x = 103
A) 0.0643 B) 0.125 C) 0.00260 D) 0.0714
Find the minimum samplesize you should use to assure that your estimate of will be within the required margin of error around the population p.
4) Margin of error: 0.002; confidence level: 93%; and unknown
A) 204,757 B) 410 C) 204,750 D) 405
5) Margin of error: 0.07; confidence level: 95%; from a prior study, is estimated by the
decimal equivalent of 92%.
A) 58 B) 174 C) 51 D) 4
Use the given degree of confidence and sample data to construct a confidence interval for the
population proportion p.
6) When 343 college students are randomly selected and surveyed, it is found that 110 own
a car. Find a 99% confidence interval for the true proportion of all college students who own a car.
A) 0.256 < p < 0.386 B) 0.279 < p < 0.362 C) 0.271 < p < 0.370 D) 0.262 < p < 0.379
Determine whether the given conditions justify using the margin of error E = when
finding a confidence interval estimate of the population mean .
7) The samplesize is n = 9, is not known, and the original population is normally distributed.
A) Yes B) No
Use the confidence level and sample data to find the margin of error E.
8) Systolic blood pressures for women aged 18-24: 94% confidence; n = 92,
x = 114.9 mm Hg, = 13.2 mm Hg
A) 47.6 mm Hg B) 2.3 mm Hg C) 2.6 mm Hg D) 9.6 mm Hg
Use the confidence level and...

...
Psychographics are the attributes that describe the personality, attitudes, beliefs, values, emotions, style, opinions of customers, and prospective customers. It helps the market to pick up the market targets, and research how markets differ from one another. It does this by distinguishing people’s life style. Magazine ads contain different symbolic messages to reach their audience. People who spend hundreds, thousands, or even millions on ads know who is reading a certain magazine. Advertisers take our attraction with pleasing images and captions to draw us in. The purpose of understanding target market and their psychographics will enable business people to advertise, market, and sell to them more effectively.
Ad agencies and companies with a large stake in their products' image have become the biggest market for psychographics. Maybelline cosmetic firm, for example, use psychographics to make sure that the image of their products and ads are in sync with their customers' self-image, says Suzanne Grayson, a cosmetics industry consultant. "The stronger that bond," said Grayson, "the stronger the franchise." In the Maybelline mascara ad, the image number one displays a beautiful young lady, dressed up in blue which appeals to women who wants to be beautiful. One of the first attraction that I noticed about this advertisement is the colors. Blue has a lot of significance in formality and elegance, especially in its deeper shades. Therefore,...

...
3
Figure 1: Generic Strategic Options
Amazon.com operates using a Hybrid Business Strategy which combines two of the abovethree strategies depending on the Business sectors it is operating within. According tocommon belief, a
ll three strategies can’t be combined especially cost leadership and
differentiation as
‘differentiation is usually costly...
conversely; cost leadership often requiresa firm to forego some differentiation by standardising the product, reducingmarketing
overhead, and the like’
(Porter, 2004, p. 18).Within the period of 2009-2012, the one market that Amazon tapped into and turned itself into a global leader was the e-book reader market. The Hybrid strategy used towards this wasthe Cost Leadership and Focus Strategy where Amazon.com created its very own e-book reader called the Kindle of which an estimated
‘200 million units
have been shippedworldwide since 2009 and another 1 billion are predicted to ship over the next five years
’
(Forbes, 2013). In terms of Kindle, Amazon introduced a new product within an alreadyexisting niche market, but made it small and innovative and advertised it through its alreadyexisting large customer base giving it the competitive advantage and attractiveness it requiredto shift units in bulk.Kindle, a very recent innovation, has propelled Amazon to new heights within the e-commerce business. Despite the innovative Kindle
receiving the Reader’s Choice award for
the best e-book...

...Samplesize
The process of determining the proper samplesize was established through a series of calculations and after obtaining all the possible samplesizes, the largest one was taken into consideration to collect the closest number to a representative sample of the population. The following two equations where used:
Equation 1:
N=z2 *(p.q)
E2
N= samplesize
Z=level of confidence interval at 95% so z=1.96
P=estimated percent of population
E=acceptable sample error expressed as a percent (5%).
Equation 2:
N=s2*z2
E2
N= samplesize
S=(minimum-maximum value) and divide the range by 6.
Z=level of confidence interval at 95% so z=1.96.
E=acceptable sample error expressed as a percent (5%).
For each question the series of calculations lead to the following results:
The samplesize for question 1 is calculated using equation 1 and n=245.8624 rounded to n=246.
The samplesize for question 2 is calculated using equation 1 and n=368.79 rounded to n=369.
The samplesize for question 3 is calculated using equation 1 and n=288.12 rounded to n=289.
The samplesize for question 4 is calculated using equation 1 and n=349.5856 rounded to n=350.
The...