ECN 221: Business Statistics Exam 2

Continuous Random Variable

can assume any value in an interval on the real line or in a collection of intervals

NORM.DIST

used to compute the cumulative probability given an x value

NORM.INV

used to compute the x value given a cumulative probability

Element

the entity on which data are collected

Population

a collection of all the elements of interest

Sample

a subset of the population

Sampled Population

the population from which the sample is taken

Point Estimation

we use the data from the sample to compute a value of a sample statistic that serves as an estimate of a population parameter

x̄ (x-bar)

sample mean

μ (mu)

population mean

σ (sigma)

standard deviation

Central Limit Theorem

the theory that, as sample size increases, the distribution of sample means of size n, randomly selected, approaches a normal distribution.

Strata

groups of elements

Clusters

separate groups of elements

Stratified Random Sampling

a form of probability sampling; a random sampling technique in which the researcher identifies particular demographic categories of interest and then randomly selects individuals within each category.

Cluster Sampling

a probability sampling technique in which clusters of participants within the population of interest are selected at random, followed by data collection from all individuals in each cluster.

Systematic Sampling

every nth item in the target population is selected

Convenience Sampling

use results that are easy to get

T Distribution

a family of similar probability distributions

Degrees of Freedom

a specific t distribution depends on a parameter known as

Confidence Coefficient

the probability that the interval contains the true parameter

Confidence Level

the confidence coefficient expressed as. percentage

Significance Level

α=1-confidence coefficient

s

sample standard deviation

To construct a confidence interval for the mean you will need

a point estimate

Given the same data set, a wider confidence interval will have a larger margin of error (T/F)

True

The margin of error in an interval estimate of the population mean is a function of all of the following except:

(a) sample size

(b) level of significance

(c) variability of the population

(d) sample mean

(d) sample mean

An interval estimate is used to estimate

a population parameter