Tuesday, April 19, 2011

Polls and Sampling

What are the 3 different types of sampling techniques that we talked about in class and what is the most important thing to consider when sampling?

Statistical Bias

A survey taken by a sample size of 1000 people asked whether each participant had ever committed theft. What possible biases could arise from this?

Means and Percentages

If the population Mean is 150 and the Standard Deviation is 30, what percentage of the population falls between 105 and 195?

If the population Mean is 150 and the Standard Deviation is 30, what percentage of the population falls between 105 and 195?

Monday, April 18, 2011

Survey Distribution Strategies!

What are some of the ways that a business can ensure that their survey will be randomly distributed?

Samples and Populations

100 K-college students are surveyed are given a survey about which movie they would like to watch for Zoo-flicks. Do the students given the survey represent a sample or a population?

Question on calculating standard error

Given that the standard deviation is 4 and the population size is 1000, calculate the standard error for the this study.

Normal distribution

What are three characteristics of a normal distribution?

Sample Variance and Standard Deviation

Calculate the sample variance and the standard deviation of the following set of numbers:


Standard Deviation

What is the disadvantage of standard deviation as a statistical tool?

Empirical Formula

What is the empirical formula used for?

Increasing accuracy of standard error

Using the equation for calculating standard error as a reference, how are researchers able to increase accuracy.

Relationship Between Variables

Find the sample covariance of the data below and tell if the variables have a direct or inverse relation.

x y
2 5
4 11
6 13
8 17
10 21

Sunday, April 17, 2011

Find the Coefficient of Variation

Calculate the coefficient of variation first finding the mean and the standard deviation using this data set:

50, 52, 38, 65, 57, 48, 60, 53, 55, 44

survey design question

In the survey questions, why should the questions be in a certain order?

How do prices of sandals vary?

Here is the list of prices ($) for sandals at payless.com:
20, 15, 25, 17, 27, 23, 10, 28

1. What is the average price of a pair of sandal?
2. How do the prices of sandals vary compared to the average price?

Cause & Correlation

What are the three reasons why variables may be correlated?

Correlation and Causation

Which one of the six different variations of the causes for the relationship between correlation and causation is false? a. two variables may be correlated because x casues y b. two variables may be correlated because y causes x c. two variables may be correlated because of an implied causation between x and y d. two variables may be correlated because they interact e. two variables may be correlated because of a lurking variable f. two variables may be spuriously related

Athletes Standard Error

If 25% of Kalamazoo College consists of athletes, and there are 1,200 students surveyed; what will be the standard error of the survey.

Standard Deviation Practice

List below are two data sets. Please calculate the sample variance and the standard deviation for each:

Advantages and Disadvantages

What are the advantages and disadvantages of the mean?

The Mode

What are the disadvantages and advantages of the Mode?

Population Studies Question

Give 2 reasons statisticians do not conduct population studies and give 2 reasons why population studies are useful.

Use the information below to answer the questions:

Stadium Capacity(thousands)
Rungrado May Day (N.Korea) 150
Salt Lake (India) 120
Beaver (Pennsylvania) 107.28
Michigan 106.2
Estadio Azteca (Mexico) 105

a) the mean
b) the variance
c) the standard deviation


In a new study on College lifestyle, a professor at K decides he will survey K students on how their lifestyles are. To get his sample the professor goes through the school's directory and picks every 25th student to use for the survey. This type of sample is:
A) Stratified random sample
B) Systematic sample
C) Cluster sample

Price of Gold

The following data represents the average prices of gold (in dollars per fine ounce) for the years 1981 to 2000. Find the mean, variance, and standard deviation of the data. What percentage of the data lies within two standard deviations of the mean?

460, 376, 424, 361, 318,
368, 478, 438, 383, 385,
363, 345, 361, 385, 386,
389, 332, 295, 280, 280

(Source: U.S. Bureau of Mines and U.S. Geological

Calculating the Standard Error

The sample mean for the cost of an accounting book is $185.00, based on a sample of 100 people. Calculate the standard error for an accounting book.

Practice Problem

A recent survey took a sample size of 10,000 people and asked them too answer questions on how much money they spend on junk food each week? With a standard deviation of $15.75, calculate the standard error.

A.) 1.25
B.) .1525
C.) .1435
D.) .1575

Saturday, April 16, 2011

Eat More Granola Bars ....... and practice more......

Calculate the sample standard deviation using the following data about Granola Bars.

Granola Bars

Price (Dollar) per Box

Nature Valley




Power Bar




Fiber One


Practice Problem

A group does a survey by calling 1,000 households in Kalamazoo. Every household number in Kalamazoo was randomized and put onto a list, the surveyors then called every 5th number. This is an example of what kind of sampling technique?

A) Simple Random Sample
B) Systematic Sample
C) Stratified Random Sample
D) Cluster Sample

Friday, April 15, 2011

Reading Preferences: Practice Problem for Exam

A study of four students found the following information:

Numbers of Fantasy Books Read (X):
Student 1: 3
Student 2: 1
Student 3: 3
Student 4: 9

Number of Biographies Read (Y):
Student 1: 4
Student 2: 4
Student 3: 8
Student 4: 8

Calculate the mean, median, mode, and standard deviation for each variable.
Calculate the covariance and correlation.

Claire V. Madill

Monday, April 4, 2011

College Admittance


Author: Jacques Steinburg
Publication Title: The Choice
Article Title: Stanford and Duke Accepted How Many? Colleges Report 2011 Admission Figures
Date: March 30, 2011

1. Jacques Steinburg
2. It is undisclosed who sponsored the survey.
3. Yes, I think whoever sponsored this survey wanted to see which colleges were more lenient in their decisions on accepting and also which colleges were harder to get into.
4. This study included the amount of applicants and of those applicants, they showed who was admitted.
5. The results are communicated very well, extremely easy to read and interpret.
6. The graph used in this article is very easy to read. I understood it the first time I looked at it.

Friday, April 1, 2011

Jake Olds - Blog Assignment #1

Blog assignment #1

Jake Olds

New York Times

Tweety Was Right: Cats Are a Bird’s No. 1 Enemy

By Elisabeth Rosenthal, March 20, 2011


1. The study was done by a few biologists and specialists in The Journal of Ornithology

2. The sponsor of this research is undisclosed

3. This sponsor was interested in finding out how disruptive cats can be to the natural environment, by killing baby gray catbirds.

4. It is not noted. However, it seems that the methodology includes a sample size of a certain number of catbirds’ deaths which were looked into to find the cause of this death. This is a random sample, there is not a control group.

5. These results are clearly communicated. 80% of the birds in the study were killed by predators. 47% of these predators were cats.

6. There are no graphs in this study.

"Education Still Pays"

"College graduates make 75% more then non-college graduates"

1. The Bureau of Labor Statistics conducted the research.
2. The United States of America revenue (from our tax dollars) probably sponsored this research.
3. This research is important to Colleges, Employers, Employees, and possible the IRS.
4. this article conveyed its information concisely and appropriately.
5. It did include graphs, which supplemented the study's findings. they are very helpful, and interesting.


Exporters' Gain Is Workers' Loss in China's Labor Market

1) This study was done by Standard Chartered PLC
2) It is not explicitly listed who sponsored this research, but presumed Standard Chartered
3) The sponsor of this study would very likely have an interest in the outcome of this study since they are a financial institution that profits from financing trade between Europe, Asia and Africa.
4) 87 manufacturing firms were surveyed during the first quarter, it doesn't say if the sample is random
5) The results are clearly indicated within the text, however not broken down to show the number of firms within each wage percentage increase
6) There are no graphs in this study

Tom Orlik
Heard on the Street: Exporter's Gain Is Workers' Loss in China's Labor Force
Wall Street Journal Online

Dissatisfied Passengers

High income fliers are unhappier with airlines, survey says.
Author: Hugo Martin.
Los Angeles Times
March 28, 2011.

1. Survey was completed by the Connecticut marketing research firm, PhoCusWright.
2. The sponsorship information was Undisclosed.
3. Well it depends on who the sponsor is. I am sure the sponsor is a major airline in the United States and there for would want to compare the overall satisfaction of its customers with the overall satisfaction of the market. With this information the sponsor could determine how they are comparing against other market competitors.
4. A sample size of 1,559 people was released, however, no other information was reported about the methodology of the survey.
5. Yeah the results are reported by an outside company and communicated very well.
6. Graphs were not used to display the results concluded in the report presented by the Los Angeles.

"India census: population goes up 1.21bn"

“India census: population goes up 1.21bn”
Claire V. Madill

1) This article describes 2011 Indian census, which collected information regarding India’s population and classified the population according to gender, religion, education, and occupation. This survey was conducted by 2.7 million Indian census officials from India, who visited 670,000 towns and villages.

2) The sponsor of this research is obviously the government of India. The government of India conducted the survey on which all of the statistics in this article are based upon.

3) The government of India could have been interested in finding an highly optimistic number regarding the total population of India. India is a rising power, and its large population is one reason many believe it will become a main power in the international political and economic system. Overestimating the population makes India seem even stronger and larger and also makes India appear like more of a competitive threat to China.
This article also mentions statistics regarding the gender gap between girls and boys in India. The Indian government might be interested in underestimating the gap or providing evidence that the gap is closing. Such a finding would make it seem like India is advancing in the way of human rights, improving the India’s prestige and appearance.

4) Not much is mentioned on the methodology of the census. The article does mention the number of officials that conducted the census (about 2.7), the approximate number of towns (7,000) and villages (600,000), and outlined some of the challenges census officials faced (large area, diverse cultures, high levels of illiteracy, large homeless population).

5) Typical of many BBC News articles, the results are communicated in a clear informative manner. The information regarding total population and the statistics regarding gender gaps are straightforwardly written. A small sidebar within the article provides a easy way to review some of the main statistics.

6) One graph is included in the article. It is used in a clear informative manner. The graph has a clear title, “Falling number of girls born in India since 1961.” Both axis of the graphs are labeled, and the source is located right underneath the graph.

"India Census: Population Goes up to 1.21bn." BBC News. British Broadcasting Corporation, 31 Mar. 2011. Web. 31 Mar. 2011. .