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Statistics > Exam 2 Study > Flashcards

Exam 2 Study Flashcards

2
Q

what is an observational study

A

observe only - no interaction or control

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3
Q

What is an experiment

A

Exert control to better understand the impact of treatments vs response.

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4
Q

What are treatments

A

what we do to the person in our experiment

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5
Q

What are explanatory variables

A

a variable that we think explains or causes changes in the response variable

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6
Q

What are response variables

A

a variable that measures the outcome or result of a study

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7
Q

What is the difference between a population and a sample

A

A population is ALL, a sample is a subset selected for study

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8
Q

Name the 6 main sampling techniques

A

Random (SRS - Simple random sample)ClusterStratifiedSystematicConvenienceVoluntary Response Survey

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9
Q

What is a cluster study

A

1 group from the population (1 class to represent entire school)

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10
Q

What is a stratified sample

A

Proportional sampling of the population (College students could be represented by undergrad and grad students. Sample should have correct percentage of each)

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11
Q

What is a systematic sample

A

Every nth person is selected

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12
Q

What is a convenience sample

A

Interviewer selects people. Mall survey

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13
Q

What is a voluntary response survey

A

Depends on individuals to initiate contact, call in polls, online polls. Not valid

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14
Q

What is bias?

A

Repeat the same experiment over and over and get the same WRONG result

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15
Q

Does sample size effect bias?

A

NO!

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16
Q

How do we correct for bias?

A

change sampling method. Must have demographics for population to reduce bias

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17
Q

What is sampling error?

A

cannot be controlled (variability). Repeating the same experiment over and over variations are sampling error.

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18
Q

How can we decrease variability?

A

Increase sample size

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19
Q

How do you computer MOE?

A

1/ Square root of sample size

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20
Q

What is a confidence interval

A

Result + or - MOE

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21
Q

Can sampling error be eliminated?

A

NO!

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22
Q

What is the difference between a parameter and a statistic?

A

Parameter refers to population and statistic refers to sample

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23
Q

What is the placebo effect?

A

Positive response independent of treatment?

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24
Q

What is the purpose of using a placebo?

A

placebo attempts to reduce bias

25
Q

What is a lurking variable?

A

something not being accounted for in the study

26
Q

What are confounding variables

A

measuring more than we need. Variables are confounding when their effects on a response variable cannot be distinguished from each other. Confounding variables can be either explanatory or lurking variables

27
Q

What 3 components are necessary for ethical human studies

A

Institutional Review BoardInformed ConsentConfidentiality

28
Q

What are explanatory variables

A

Controlling the response (what we are changing)

29
Q

What are response variables

A

The outcome of the experiment - what we are measuring

30
Q

What is reliability

A

measure same person, same way get same result. Results can be both reliable and biased

31
Q

What is rate?

A

change/time - more valid measure than a simple count of occurrences (response/population)

32
Q

What is a block design (and can you draw one)

A

random assignment of subjects to treatments is carried out separately within each block. (eg: group (block) patients based on disease and then randomly assign to different treatments)

33
Q

Does an observational study have a design?

A

NO!

34
Q

What is a randomized comparative experiment (and can you draw one)

A

All subjects are allocated at random among all the treatments. eg: all subjects randomly receive either coke, pepsi or RC cola - response variable is BMI - no blocking

35
Q

What is a matched pair design?

A

matched pair compares two treatments eg: does coke or pepsi taste better or it could be two subjects each getting one treatment.

36
Q

Give 3examples of nonsampling errors

A

nonresponse, response error(inaccurate response), processing errors

37
Q

what is a sampling frame

A

list of the subjects

38
Q

what is statistical significance?

A

an observed effect of a size that would rarely occur by chance.

39
Q

what is quantitative

A

numbers with meaning

40
Q

what is qualitative

A

numbers without meaning (index)

41
Q

What is a pareto chart

A

Bar chart

42
Q

What is another name for a qualitative variable

A

categorical variable

43
Q

What is Mean

A

average

44
Q

what is median

A

middle number

45
Q

what is mode

A

most frequent

46
Q

What is standard deviation

A

average distance a data point varies from the mean - Shows spread/variability of data

47
Q

what controls the MOE

A

sample size only

48
Q

What is the formula for a z score

A

z = number minus average then divided by std deviation

49
Q

Skewed left where is average

A

left of median

50
Q

skewed right where is average

A

right of median

51
Q

what are the types of stem/leaf

A

skewed left, skewed right, symmetrical

52
Q

what is inverse norm used for

A

finding number when we have area or %

53
Q

what is normalcdf used for

A

finding percentage area

54
Q

greek letters reference

A

population!

55
Q

What does the greek letter Sigma signify

A

std deviation for population

56
Q

What are the std dev percentage rules

A

68% within 1 std dev
95 % within 2 std dev
virtually all within 3 std dev

57
Q

test question

A

this is a test

Statistics (4 decks)

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