Flashcards in Quiz5ch11&12 Deck (34)

Loading flashcards...

1

## What is the difference between a sample and a census?

### A sample is a subset of all members of a population and a census is data from about every member of the population

2

## What are the seven steps in devloping a sample plan?

### 1) define target population, 2)choose data collection method, 3) select sample frame, 4)obtain sample, 5) determine sample size, 6) select sample units, 7)Conduct fieldwork

3

## What is one thing you should always do when defining populaion of interest?

### Create screening questions to eliminate individuals who do not belong

4

## What is a sampling frame?

### A list of elements from which units to be sampled are selected

5

## What are some examples of sampling frames?

### Telephone book, customer list, random-digit dialing

6

## What are the two major sampling methods?

### Probability and nonprobability samples

7

## What is a probabilty sample?

### A known, nonzero probabilty of selection

8

## What are four types of probability samples?

### Systematic, stratified, cluster, simple random

9

## What is a nonprobability sample?

### Elements selected in a nonrandom manner (convenience)

10

## What are four types of nonprobability samples?

### Convenience, snowball, judgment, quota

11

## What are three advantages of a probabilty sample?

### Information from a representative cross-section, sampling error can be computed, results are projectable to the total population

12

## What are errors that results when the same sample is not perfectly representative of the population?

### Sampling Error

13

## What is the formula for computing the simple random probabilty of selection?

### Sample size / Population size

14

## What sampling uses fixed skip intervals to draw elements from a numbered population?

### Systematic Sampling

15

## What is the formula for a skip interval?

### Population Size / Sample Size

16

## What are the steps in implementing a properly stratified sample?

### 1) Identifiy salient demographic or classification factors to correlate behavior of interest, 2) determine what % of pop. Fall into subgroups, 3) Select separate simple random sample

17

## What are the two basic steps in cluster sampling?

### 1) Population of interest is divided into mutually exclusive subsets, 2) a random sample of subsets is selected

18

## What is a nonprobabilty sample used to select additional respondents on the basis of referrals?

### Snowball samples

19

## What are general rules about determining sample size?

### Larger sample-smaller error, larger sample cost more on linerar basis, before trying to determine size of sample you must decide confidence interval

20

## What happens as sample size gets smaller?

### Sampling error increases

21

## What do you need to calculate sample size?

### 1) an estimate of standard deviation, 2) acceptable level of sampling error, 3) confidence interval

22

## What is the distribution of a large number of sample means or sample proportions will approximate a normal distribution called?

### Central Limit Theorem

23

## What are four important characteristics of a normal distribution?

### 1) bell shaped and one mode, 2) symmetrical about the mean, 3) defined by its mean and standard deviation, 4) area =1

24

## What is the formula for z score?

### (Value of variable - mean of variable) / standard deviation

25

## What are the percentages for the area under the curve for z values 1,2,3?

### 68%, 95%, 99%

26

## What is the formula to calculate the standard error of the mean (standard deviation)?

### =Standard deviation / SQRT(n)

27

## What are the steps in calculating confidence interval?

### 1) calculate mean, 2)estimate standard deviation, 3) estimate standard error, 4) estimate z value, 5) calculate

28

## What are four methods used to deal with the estimate of population standard deviation?

### 1) use results from prior survey, 2) conduct pilot survey, 3) use secondary research, 4) Use judgement

29

## What is the formula for calculating sample size based on a proportion or precentage?

### n = (Z^2 * (P(1-P))) / E^2

30