Ch. 17: Determination of Sample Size 6ekl

Descriptive Statistics

Summarize and desrcibe the data in a simple and understandable manner

Inferential Statistics

To project characteristics from a sample to an entire population

Sample Statistics

• Variables in a sample or measures computed from sample data

• : Portion of population

Population Parameters 

• Variables of a population or measured characteristics of the population 

• Judgement about a population

• Rep as X or S in Greek 

Frequency Distribution 

• Set of data organized by summarizing the number of times a particular value of a variable occurs 

• Recording a number of times a value of a variable occurs 

• : Amount withdrawn from an ATM 

Percentage Distribution

• Frequency distribution organized into a table or graph that summarizes percentge values associated with values of a variable 

• : Percentage of people who withdrew a certain amount from an ATM 

Probability

• Long run relative frequency with which an event will occur

• : Chance of someone withdrawing more than 10k 

Proportions

• Percentage of elements that meet some criterion 

• : Portion of CPAs in an accounting firm 

Standard Deviation

Variability, square root of the variance for a distribution 

Variance

• Measure of variance or dispersion

• Square root is the standard deviation

Normal Distribution

• Symmetrical bell-shaped distribution

• Expected probability distribution of many chance occurrences

Population Distribution 

Frequency distribution of the elements of a population

Sample Distribution

A frequency distribution of a sample

Central Limit Theorem

• As sample size increases the distributionof sample of means of size n, randomly selected approached a normal distribution

Point Estimate

An estimate of the population mean in the form of a single value, usually the sample mean

Confidence Internal Estimate 

A specified range of numbers within which a population mean is expected to lie; an estimate of the population mean based on the knowledge that it will be equal to the sample mean plus or minus a small sampling error

Confidence Level 

A percentage or decimal value that tells how confident a researcher can be about being correct; it states the long-run percentage of confidence intervals that will include the true population mean