111) Pre Exam

Question 1

Basics of Statisitics: The main purpose is to create relevant? To obtain main purpose, statistics uses methods of? Statistical Analysis? population, sample, subject?

Answer 1

• To create relevant data. The observations gathered on the characteristics of interest are collectively called data. - Specifically, statistics provides methods for: 1. Design. Planning how to gather data for research studies 2. Description’. Summarizing the data. Summarized data as tables, graphs, pictures is part of descriptive statistics. 3. Inference. Making predictions based on the data - Description and Inference are parts of statistical analysis. Population total set of entities >> Sample is a subset of population >> Subject is observed entity.

Question 2

Inferential Statistics?

Answer 2

Inferential statistics provide a prediction about the larger population using the sample data.

Question 3

Descriptive statistics?

Answer 3

Descriptive statistics are brief descriptive coefficients that summarize a given data set, which can be either a representation of the entire or a sample of a population.

Question 4

1. What is “Variable”?
2. When variable is called “Quantitative”?
3. When variable is called “Categorical”?
   Also so called qualitative.
   Qualitative = Categorical

Answer 4

1. Any characteristic we can measure for each subject.
   Variable can vary in value among subjects in a sample or population.
2. When the measurement scale has numerical values.
3. When the measurement scale is a set of categories.

Question 5

What type of scales are applied for categorical values?

Answer 5

> Nominal scale where categories do not have “high” or “low” end.

> Ordinal scale where categories have a natural ordering of values.

Question 6

1. What is Normal or “Gaussian” distribution?
2. What tells standard deviation about curve of normal distribution?
3. Why knowing standard deviation is helpful?
4. What do you need to know to draw normal distribution?

Answer 6

1. It is symmetrical “bell shaped curve”.
2. It tells Width of the curve.
3. It is helpful to know standard deviation because normal curves are drawn such that 95% of the measurements fall between +/- 2 standard deviations around the mean.

4.

> The average measurement (mean), this telles where the center of the curve goes.

> The sdandard deviation of the measurements, this tells how wide the curve should be. (wider>shorter, narrower>taller).

Question 7

The Mean?

What is median?

What is Mode?

Answer 7

1. AVERAGE. The best known and most commonly used measure of the center is the mean. Mean is the sum of the observations divided by the number of observations.
2. The median is the observations that falls in the middle of the ordered sample. When the sample size n is odd, a single observation occurs in the middle. When the sample size is even two middle observations occur, and the median is the midpoint between two.
3. The mode is value that occurs most frequently.