Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Public Health > Biostats > Flashcards

Biostats Flashcards

(49 cards)

Start Studying
1
Q

What is the name given to a descriptive measure computed from the data of a sample?

A

A statistic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the name given to a descriptive measure computed from the data of a population?

A

A parameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

If a distribution is skewed to the right, what is the relationship between mean, median and mode? Where is the tail of this graph?

A

Mode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

If a distribution is skewed to the left, what is the relationship between the mean, median and mode? Where is the tail of this graph?

A

Mode > Median > Mean

Tail is on the left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does a 95% confidence interval imply in theoretical probabilistic terms?

A

That in repeating sampling from a normally distributed population, 95% of all intervals will (in the long run) include the true population mean

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does a 95% confidence interval imply in practical terms?

A

We are 95% confident that the interval will include the true population mean

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Null hypothesis

A

Means are equal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Alternative hypothesis

A

Means are different

Usually synonymous with research hypothesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a Type I error?

A

When we reject the null hypothesis, although the null is true (“Null = no wolf. Therefore Type I = False alarm”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What symbol is the probability of a Type I error denoted by?

A

a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do we call the quantity 1-a?

A

The level of confidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a Type II error?

A

When we fail to reject the null hypothesis when the null is false (“Null = no wolf. Therefore Type II = Failing to raise the alarm”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What symbol is the probability of a Type II error denoted by?

A

B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do we call the quantity 1-B?

A

Statistical power of the test (probability of rejecting the null hypothesis when it is false)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a P value?

A

A measure of how much evidence we have against the null hypothesis. The smaller it is, the more evidence we have against the null.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does P>0.05 mean?

A

That we cannot reject the null hypothesis as we have insufficient evidence to do so. This does NOT necessarily mean that the null hypothesis is true, only that there is insufficient evidence to reject it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a paired t-test used to do?

A

It is used to determine whether there is a significant difference between paired observations, for example, before and after an intervention.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the significance of a confidence interval that crosses 0?

A

If the 95% confidence interval for the difference between two means includes zero, then the hypothesis test WILL give a statistically non-significant result (p>0.05)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a variable?

A

Any aspect of an individual that is measured or recorded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a categorical variable?

21
Q

What is a numerical variable?

22
Q

What is the relationship between mean, median and mode in a symmetrical distribution?

Study These Flashcards
A

They are approximately equal/very similar

23
Q

What percentage of observations are included in the following ranges of a normal distribution:
mean ±1, 2 and 3 standard deviations of the mean?
What is another name for these values?

Study These Flashcards
A

1: ±68%
2: ±95%
3: ±99%
These can also be referred to as the probability limits

24
Q

What is a synonym for a sample statistic?

Study These Flashcards
A

Point estimate

25
What is the name given to the measurement of the degree of variation between means from repeated samples? How is this calculated?
Standard error of the mean | SEM = SD/sqrt(n)
26
How is a 95% confidence interval calculated?
mean±1.96*SEM
27
What is standard error?
A measurement of the precision of estimates. It shows how good the estimation of the mean is (SEM)
28
What is standard deviation?
A measurement of the variability of distributions. It shows how widely scattered the measurements are (SD)
29
When is a result inconclusive?
When a sample size is too small to declare an observed effect to be statistically significant
30
When is a result imprecise?
If a small sample size results in wide confidence limits
31
What does a t-test measure?
The difference between two means from independent samples of numerical variables
32
What are the underlying assumptions of a valid t-test?
- Sampled populations are normally distributed | - Standard deviations are similar
33
What is the non-parametric equivalent of a t-test and when is this used?
- Wilcoxon sum of rank test | - It is used when there is an obvious non-normal data set
34
What does a Chi-squared test measure?
The relationship between two categorical variables, and the differences in proportions
35
What is the purpose of Pearson's correlation?
To measure the degree of association between two numerical variables
36
Binary variable
Categorical Observations fall under one of two categories e.g. exposed vs non-exposed
37
Nominal
Categorical Observations fall under more than two categories e.g. classification of disease; marital status
38
Ordinal
Categorical Observations fal under more than two categories which can be ordered e.g. classification according to mild, moderate, severe
39
Continuous data
Numerical Data are measurements that can assume any value within a a specified range e.g. height, weight, blood pressure
40
Discrete data
Numerical Data are integers/counted numbers of events e.g. number of births in a week, number of patients in a clinic
41
Which summary statistics are reported if a data set is symmetrically distributed?
Number of observations Mean Standard deviation
42
Which summary statistics are reported if a data set is skewed?
Number of observations Median Range Interquartile range
43
What is a population?
A group of individuals having certain common characteristics about which statistical inferences can be made
44
What is a sample?
A subset of individuals selected from a defined population
45
Benefits of sampling
Less time to collect and analyse data Greater flexibility in data management and type of information that can be obtained Reduce cost
46
Random sampling
Each individual in the population has an equal | chance of being included in the sample
47
Stratified sampling
Stratified sampling is used when the population consist of distinct sub-groups or strata, which differ considerably with respect to the main feature under study
48
Systematic sampling
A process where individuals are selected systematically throughout the series on a basis of a predetermined sampling fraction
49
Cluster sampling
Study population is divided into clearly defined groups or clusters (example: street-blocks or areas around informal housing units) A random sample of clusters are drawn

Public Health (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions