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Epi Exam 3!! > Intro to Biostats- Week 1 > Flashcards

Intro to Biostats- Week 1 Flashcards

1
Q

What are the three steps of data measurements in human studies?

A
  1. Data will be collected on desired variables.
  2. Comparisons are commonly made. (statistical analysis)
  3. Inferences will be made about the sample-derived ‘data’ and their comparisons. (null hypothesis)
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2
Q

Researchers will either accept or not accept this, based on statistical analysis?

A

Null Hypothesis (H0)

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3
Q

What is a Null Hypothesis?

A

A research perspective that states there will be no (true) difference between the groups being compared.

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4
Q

What are the three statistical perspectives that can be taken by the researcher? (in relation to null hypothesis?)

A
  1. Superiority
  2. Noninferiority
  3. Equivalency
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5
Q

What are the three key attributes of data management?

A
  1. Order/Magnitude
  2. Consistency of scale/ equal distance
  3. Rational absolute Zero
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6
Q

What are the three primary levels for variables based on three key attributes?

A
  1. Nominal
  2. Ordinal
  3. Interval or Ratio
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7
Q

Describe “Nominal” in relation to the three primary attributes of data management.

A
  1. No order or Magnitude
  2. No consistency of scale
  3. No quantitative characteristics
    (Nominal variables are labeled-variables without quantitative characteristics)
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8
Q

Describe “Ordinal” in relation to the three primary attributes of data management.

A
  1. Yes order of Magnitude
  2. No consistency of scale
  3. No units
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9
Q

Describe “Interval/Ratio” in relation to the three primary attributes of data management.

A
  1. Yes order of magnitude
  2. Yes consistency of scale
  3. Yes absolute zero, but they are different for both.
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10
Q

Describe the difference between “Interval” and “Ratio”

A 
Interval = Arbitrary zero value (0 doesn't mean absence)
Ratio = Absolute (rational) zero value (0 means absence of measurement value)
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11
Q

All statistical tests are selected based on what?

A

Level of data being compared

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12
Q

After data is selected you can go up/down in specificity of data measurement levels, but never up/down?

A
  1. down

2. up

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13
Q

Data is represented by what in quantitative study designs?

A

Numbers

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14
Q

Data is represented by what in qualitative study designs?

A

Words

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15
Q

What is descriptive statistics?

A

Non-comparative, simple description of various elements of the study’s data

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16
Q

What is the mean of a data set?

A

The usual average, add all numbers and divide by the amount of numbers in the set

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17
Q

What is the median of a data set?

A

The median is the middle value of the data set, when they are aligned in numerical order.

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18
Q

What is the mode of a data set?

A

The mode is the number that is represented more than any other number of the data set.

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19
Q

What is the Range of a data set?

A

the range is the maximum minus the minimum

20
Q

What is the Interquartile range? (IQR)

A

The interquartile range is the difference between two different quartile points, for example the 25th percentile is 10 and the 75th percentile is 20, Q3 - Q1 = 10.

21
Q

What is Variance?

A

the average of the squared-differences in each individual measurement value (x) and the groups’ mean.

22
Q

Standard Deviation

A

square root of Variance value (restores units of mean)

23
Q

A normally distributed graph is what?

A

symmetrical

24
Q

What does it mean when a graph is symmetrical?

A

It is when a dataset is normally-distributed the following values (PARAMETERS) are equal/near equal

25
Q

What type of stat tests are useful for normally-distributed data?

A

Parametric tests

26
Q

What is an asymmetrical distribution?

A

When one tail of the graph is longer than another tail

27
Q

What makes a graph positively skewed?

A

mean>median

28
Q

What makes a graph negatively skewed?

A

Median>Mean

29
Q

What is skewness?

A

a measure of the asymmetry of a distribution.

30
Q

A perfectly-normal distribution that is symmetric will have a skewness value of what?

A

0

31
Q

What is Kurtosis?

A

A measure of the extend to which observations cluster around the mean.

32
Q

A normal distribution will have a kurtosis value of what?

A

0

33
Q

A positive kurtosis value means what?

A

more cluster around the mean

34
Q

A negative kurtosis value means what?

A

less cluster around the mean

35
Q

How much of the range of data is shown within the first standard deviation?

A

68%

36
Q

How much of the range of data is shown within the first two standard deviations?

A

95%

37
Q

How much of the range of data is shown within the first three standard deviations?

A

99%

38
Q

In nominal and ordinal data the mean represents what?

A

nothing. you can’t use it because the numbers have no meaning.

39
Q

What are the two required assumptions of interval/ratio data?

A
  1. normally distributed

2. equal variances

40
Q

What is a test we can do to describe the two required assumptions of interval/ratio data?

A

Levene’s test

41
Q

What does Lavene’s test show?

A

calculate if groups are normally distributed with equal variance

42
Q

How can we handle data that is not normally-distributed?

A
  1. Use a statistical test that does not require the data to be normally-distributed (non-parametric tests)
  2. Transform data to a standardized value (z-score or log transformation) (in hopes that transformation allows data to be normally-distributed)
43
Q

Researchers either accept or don’t accept WHAT based on statistical analysis?

A

Null Hypothesis

44
Q

What is Type 1 error?

A

Not accepting the null hypothesis when it is actually TRUE, and you should have accepted it!

45
Q

What is type 2 error?

A

Accepting the null hypothesis when it is actually false, and you have NOT accepted it.

46
Q

In which type of error is there no true differences between the groups, but in error you did not accept the Null Hypothesis.

A

Type 1

47
Q

In which type of error is there a true difference between the groups, but in error you accepted the null hypothesis?

A

Type 2

Epi Exam 3!! (5 decks)

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