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Stats > Chapter 5 > Flashcards

Chapter 5 Flashcards

1
Q

What is the purpose of inferential stats

A

used to learn about the population from a sample

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2
Q

two types of inferential stats

A

estimation
hypothesis testing

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3
Q

Parameter

A

mathematical characteristics of populations

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4
Q

A survey was conducted on 500 students from a population of 20,000 students at a university. It found that 74% of students were employed during the semester.
determine the
population
sample
statistic
parameter

A

population= 20,000 students
sample= 500 selected for interviews
statistic= 74% sample that held a job during the semester
parameter= % of all students in the population who held a job

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4
Q

Statistics

A

mathematical characteristics of samples

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4
Q

What is a random sample

A

every case in the population has the same chance of being selected

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4
Q

What is a representative sample

A

a sample that reproduces important characteristics of the population

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4
Q

What does EPSEM stand for and what does it mean

A

equal probability of election methods

Every element or case in the population must have an equal probability of being selected

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5
Q

What is a non random sample

A

lack equal or known probability of selection

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6
Q

sampling frame

A

the list of elements from which the sample will be selected

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7
Q

Probability sample

A

a sample selected using a random process so that each element in the population has a known likelihood of being selected

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8
Q

How to select a simple random sample

A

Number all the elements consecutively starting at 1.
Pick a sample size (n) from the total population (N).
Using a random number table or computer program to generate a list of random numbers.
The sample will be comprised of the cases whose element numbers match the randomly generated numbers.

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9
Q

Sampling distribution

A

the theoretical probabilistic distribution of a statistic for all possible samples of a given size

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10
Q

three distributions of inferential statics

A

sample
population
sampling distribution

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11
Q

Example of the concept of sampling distribution

A

-draw a ample of ten people from a population of 100 multiple times
-calculate the mean age for each of these samples
-each sample will have a different outcome

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12
Q

characteristics of a sampling distribution

A

-normal in shape
-mean equal to the population mean
-SD equal to the population SD
σ/n.

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13
Q

As n becomes large…

A

the sampling distribution of a sample mean will approach normality with a mean and SD of σ/n.

14
Q

If n is to small…

A

you can’t apply statistics

15
Q

Importance of Central Limit Theorem

A

it removes the constraint of normality in the population

16
Q

What should a sample size generally be

A

100 or more

17
Q

The larger the sample size…

A

the more normal the curve gets

18
Q

Sampling distribution

A

distribution of a statistic for all possible outcomes of a certain sample size

19
Q

mean of the sampling distribution of means =

A

population mean

20
Q

standard deviation of sampling distribution=

A

population standard deviation divided by the square root on n

21
Q

systematic sample

A

every “i” the case in the sampling frame is selected

22
Q

stratified random sample

A

this type of sampling ensures that subgroups in the population are proportionally represented in the sample

23
Q

how to select a stratified random sample

A

divide into subgroups
select a simple random sample or a systematic sample form each stratum

If there are 80 students and 20 staff you wouldn’t choose 5 from each you would take 2 staff and 8 student’s

24
Q

multistage cluster sampling

A

select clusters
then select subunits within the cluster

                 Canadians provinces                           territories yukon, nunavut                   sask, alberta
25
Q

Example of a multi stage cluster sample

A

select a few provinces
select a random subunit from each
choose a city
choose a street
choose a house
choose someone from the household

26
Q

3 qualities of a probability sample

A

representative allows for generalization from a sample to population

inferential statistical tests

sample means can be used to estimate population means

27
Q

convenience sampling

A

cases are included because they are readily available

asking only people you see walk down the hallway

28
Q

snowball sampling

A

researcher makes contact with some individuals who in turn provide contacts for other participants

Ask an addict a question and he sends you to another addict and they send you to another addict

29
Q

Quota sampling

A

collecting a specified number of cases in particular categories to match the proportion of cases in that category in the population

you can learn from it but can’t apply it to the general population

30
Q

the ______ determines whether the sample is a random sample

A

selection process

31
Q

The sales representatives employed by a large pharmaceutical firm are numbered sequentially. From those numbers, a computer program is used to select 30 random numbers. A sample of 30 reps whose numbers correspond to those randomly selected numbers is obtained.

A

Simple random sample

32
Q

A sampling method in which one of the first k individuals and then every kth individual thereafter is selected

A

Systematic random sample

33
Q

A sampling method in which groups naturally occurring in the population are randomly selected and a subsample of these cases within each selected unit is sampled

A

Cluster sample

34
Q

A sampling method in which some cases in the population, because of the way the sample is chosen, will not have a chance of being included in the sample

A

Non-probability sample

35
Q

A sampling method in which the population is first divided into a sublist based on a relevant trait, and a simple random sample is then taken from each group

A

Stratified random sample

36
Q

Representative

A

The quality a sample is said to have if it reproduces the major characteristics of the population from which it was drawn

37
Q

What is a simple, random sample

A

A method for choosing cases from a population in which every case has an equal chance of being included

38
Q

Standard error

A

The standard deviation of a sampling distribution

Stats (12 decks)

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