Flashcards
Module 4
Cards in this deck (15)
- 1Self-selected samplesOften biased because the individuals who participate are more keenly interested in the issue than other members of the population
ex: radio stations asks people to call in to give opinion on a topic...only people interested in the issue are going to take the time to call in and give their opinion. Whereas the target population is made up of all people listening - 2Stratified Random Samplewhen the population is divided into mutually exclusive sets, or strata, and a simple random sample is then drawn from each set
- 3Cluster Sampleis a simple random sample of groups or clusters of elements
- 4Simple Random Sampleis a sample selected in such a way that every possible sample with the same number of observations is equally likely to be chosen
- 5Discrete dataconsist of counts of events, such as the number of audited invoices
- 6continuous datarefer to measurements where there are an infinite number of possible values.
- 7normal distribution•The random variable is continuous and may take on any value between minus infinity and plus infinity.
•The shape of the probability distribution is symmetric, centred on the mean, µ, or expected value of the random variable. Because the shape is often described as a bell, it is often referred to as the bell curve.
•The distribution is characterized by its mean (µ) and standard deviation (σ). - 8The standard normal distributionhas a mean of zero and a standard deviation of one.
- 9t distributionuse when the population standard deviation, σ, is unknown. the Student t distribution is a continuous probability distribution. It has a mound shape and is symmetrical around the mean, which is zero. Standard deviation is greater than 1
Since the t distribution is symmetrical, you find values of t to the left of the mean in exactly the same way. Insert a minus sign in front of the t-value for values to the left of the mean. - 10primary datadata that is collected by the organization directly
- 11secondary dataData published by an organization other than the organization that collected them
- 12experimental studiesthere is an effort to control all the variables that influence a certain outcome. For example, scientists working in a laboratory can control the temperature, the humidity, and so on, prior to conducting an experiment
- 13observational studiesexternal factors that could influence the outcome are not controlled.
- 14Sampling errorsoccur because the characteristics of the items in the sample are not an exact replica of the characteristics of the items in the population. Sampling errors occur in all data collection efforts unless the entire population is examined
- 15nonsampling errorssuch as entering the wrong data into a computer program. three types of nonsampling errors on:
- errors in data acquisition
- non response error
- selection bias
These errors cannot be measured statistically and can distort the conclusions from the study.
Information
- Description
- Professional Designation QU1 (Module 4: Normal probability distribution and sampling) Flashcards on Module 4, created by jbbacik on 13/01/2015.
- Created by
- jbbacik
- Views
- 2
- Rating