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LECOM Biostats MS1 > Intro to Biostats--Lectures 1&2 > Flashcards

Intro to Biostats--Lectures 1&2 Flashcards

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1
Q

What is the first step to take when developing research

A

Develop a hypothesis

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2
Q

What are the 4 steps of hypothesis testing

A
  1. Formulate a hypothesis
  2. Set criteria for decision
  3. Gather data and conduct statistical analysis
  4. Make decision (accept or reject)
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3
Q

What is a null hypothesis

A

States that two variables are not related

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4
Q

What are the two types of hypothesis used in hypothesis testing

A

Null hypothesis

Alternative hypothesis

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5
Q

What does a null hypothesis assume

A

no difference
all samples from some population
observed difference is due to chance
random sampling variation

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6
Q

What does an alternative hypothesis assume

A

at least one sample is from a different population

difference is not due to chance

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7
Q

How do you use a null hypothesis for testing

A

You try to disprove H0

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8
Q

If the probability of our result is less than alpha, then what is unlikely

A

that all samples came from the same population

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9
Q

What is alpha normally

A

0.05

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10
Q

When is a blood count considered normal

A

if value is found in 95% of the population and if independent of other tests

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11
Q

What are the two types of probability

A

mutually exclusive

independent

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12
Q

What is mutually exclusive probability

A

only one event can occur
either or
not both

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13
Q

What is independent probability

A

both things occur independently so you can have both

one even has no effect on the occurence of the other

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14
Q

How do you calculate mutually exclusive probabilities

A

addition rule

probability of X + probability of Y

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15
Q

How do you calculate independent probabilities

A

multiplication rule

probability of X x probability of y

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16
Q

What is sampling in statistics

A

selection of study subjects who will be measured on some parameter to provide information about population

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17
Q

What are the different sampling techniques

A 
simple random
stratified
systematic
multistage
convenience
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18
Q

What is the ultimate goal in sampling

A

want to avoid selection bias

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19
Q

What is selection bias

A

not giving people an equal chance to be selected

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20
Q

How is simple random sampling performed

A

each individual has an equal chance of having their name selected (draw names out of a hat)

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21
Q

How is systematic sampling done

A

select at regular intervals through ordered list

pick random number (k) and select kth person

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22
Q

What is stratified sampling

A

Separate people into strata and then select a sample from each group
keep the proportion of participants from each stratum equal

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23
Q

What is multistage sampling

A

combines more than 1 sampling

surveys sent out to randomly selected sample; from those answers select a more detailed survey

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24
Q

What are the types of variables based on how data is measured

A

Qualitative, quantitative

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25
What are the variables based on study design
dependent and independent
26
What are the different types of qualitative (categorical) variables
Nominal Dichotomous Ordinal
27
What are nominal variables
multiple categories with no difference in quality
28
What are dicotomous variables
only two labels for variable
29
What are ordinal variables
ranked variables
30
What are the different types of quantitative variables
Interval | Ratio
31
What is an interval variable
any quantitative vale
32
What is a ratio variable
has meaning
33
What are independent variables
input; manipulated
34
What are dependent variables
outcome, response, predicted
35
What is the standard P value that should be used in hypothesis testing
P<0.05
36
What are the measures of central tendency
mean median mode
37
What are the measures of dispersion
range, interquartile range, percentiles, SEM, SD, kurtosis, skewness, Confidence interval, Power, errors
38
What is sample size and how does this affect statistical power
larger sample sizes tend to have more statistical power
39
How do mean and median relate to distribution of a data set
if the same= normal distribution | if not the same= not normal distribution
40
What is the function of descriptive statistics
describes data without generalizing population
41
What is variance
spread of data
42
What does 0 variance mean
identical values
43
What is range
highest and lowest values
44
What is interquartile range
difference between 25th and 75th percentiles
45
What is standard deviation
square root of the variance
46
How is standard error of the mean calculated
SD/ squareroot of sample size
47
What will the SEM be in bigger groups compared to smaller groups
larger n= smaller SE
48
How can we reduce variance
increase sample size better define our sample populations censor outliers
49
What are the different types of normal unimodal distributions
Gaussian Distribution | Bell-shaped curve
50
What are the different types of skewed unimodal distributions
left-skewed | right-skewed
51
Describe a normal bell-shaped curve
1 standard deviation above and below the mean will include 2/3 of the data 95% will be within 2 standard deviations above and below the mean
52
What is a skewed distribution
mean not equal to median
53
What is a better measurement of the middle of the data in a skewed distribution
median
54
What is a positive skew
right tail is longer; most values near y axis | mean> median> mode
55
What is a negative skew
left tail is longer; most values on the right | mean< median< mode
56
What is kurtosis
the "peakedness" of the distribution
57
What is confidence interval
range of values in which a specified probability of the means of repeated samples would be expected to fall
58
What are the different types of error
``` Type 1 (alpha) Type 2 (beta) ```
59
What is a Type 1 alpha error
probability of rejection H0 when it is true
60
What is a Type 2 beta error
probability of accepting H0 when it is false
61
What is the probability of Type 1 error
false positive rate
62
What is the probability of Type 2 error
false negative rate
63
What is Power
probability of NOT committing Type II error
64
How is Power calculated
1-beta

LECOM Biostats MS1 (3 decks)

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