1. Learning Journal Reflective Comments:

Write short reflective comments or notes about your learning activities during the week. It is highly recommended that you make these entries on a daily basis. You will be assessed on the completeness of your Learning Journal, and the quality of your self-reflection.

You should date each entry, and use clear titles and sub-headings.These entries should be brief, direct sentences indicating quick comments or notes such as:

* when you completed each step in the Learning Guide during the week,

* any problems or unexpected events that occurred during the week (including

problems understanding new or old material), and

* any other noteworthy that might affect your performance in this class.

There is no need to include personal information or details of family events, but be sure to mention the existence of any situations that will positively or negatively affect your ability to focus on the classwork.

2. Vocabulary and R functions

Enter the following command in R to read a simple help page about the table() command (this is for your information, you do not need to show the output):

?table

Now enter the following command and describe the output of the table() command.What does the first row of numbers in table() output represent?What does the second row of output represent?

x <- c(5, 8, 4, 1, 5, 6, 5, 9, 4, 2, 5, 7, 5, 3, 6, 4, 5, 3, 7, 6)

table(x)

[optional: You can test your theory by altering the numbers and rerunning the table command.]

3. Task(References: Question 1.1 ..page 10-12 and self-Quiz Unit 1 Question 6 and 7)

a) Read the below inside the quotaion marks

"In statistics, we generally want to study a population. You can think of a population as an entire collection of persons, things, or objects under study. To study the larger population, we select a sample. The idea of sampling is to select a portion (or subset) of the larger population and study that portion (the sample) to gain information about the population. Data are the result of sampling from a population.

Because it takes a lot of time and money to examine an entire population, sampling is a very practical technique. If you wished to compute the overall grade point average at your school, it would make sense to select a sample of students who attend the school. The data collected from the sample would be the students' grade point averages. In presidential elections, opinion poll samples of 1,000 to 2,000 people are taken. The opinion poll is supposed to represent the views of the people in the entire country. Manufacturers of canned carbonated drinks take samples to determine if the manufactured 16 ounce containers does indeed contain 16 ounces of the drink.

From the sample data, we can calculate a statistic. A statistic is a number that is a property of the sample. For example, if we consider one math class to be a sample of the population of all math classes, then the average number of points earned by students in that one math class at the end of the term is an example of a statistic. The statistic can be used as an estimate of a population parameter. A parameter is a number that is a property of the population. Since we considered all math classes to be the population, then the average number of points earned per student over all the math classes is an example of a parameter.

One of the main concerns in the field of statistics is how accurately a statistic estimates a parameter. The accuracy really depends on how well the sample represents the population. The sample must contain the characteristics of the population in order to be a representative sample.

Two words that come up often in statistics are average and proportion. If you were to take three exams in your math classes and obtained scores of 86, 75, and 92, you calculate your average score by adding the three exam scores and dividing by three (your average score would be 84.3 to one decimal place). If, in

1.6. THE R PROGRAMMING ENVIRONMENT 7

your math class, there are 40 students and 22 are men and 18 are women, then the proportion of men students is 22/40 and the proportion of women students is 18/40. Average and proportion are discussed in more detail in later chapters."

If you were a teacher and had 30 students in your class and wanted to know the class average on the first quiz, would you use a parameter or a statistic?Why?

b) If you wanted to know how many people in your country recognize the name of your new company, would you use a parameter or a statistic?Why?