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Definitions Flashcards

1
Q

What happens in inductive reasoning?

A

From a specific premise to general conclusions

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2
Q

What happens in deductive reasoning?

A

From a general premise to specific conclusions

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3
Q

What is the definition of a hypothesis?

A

Statement that is tested by investigation (preferably experimental), in contrast to a model or theory

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4
Q

What is a research hypothesis?

A

A hypothesis derived from questions, models and theories

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5
Q

What is a statistical hypothesis?

A

Come from statistics and represent tests of the predictions of the research hypothesis

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6
Q

What is a sample study?

A

Estimate the value of a parameter for a population

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7
Q

What is an observational study?

A

Explain how two population parameters relate to each other without interfering or affecting the individuals

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8
Q

What is an experiment?

A

Intervention to explore causality

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9
Q

What is sample or empirical distribution?

A

The pattern that the data makes

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10
Q

What is Population distribution?

A

The pattern that the whole group of interest makes

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11
Q

What is uncertainty?

A

The region in which the parameter could fall

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12
Q

What is the sampling distribution?

A

The sample distribution of a statistic

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13
Q

What is kurtosis?

A

Sharpness of the peak of a frequency-distribution curve

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14
Q

What is a type 2 error?

A

Not rejecting a false H0

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15
Q

What is a type 1 error?

A

Incorrectly rejecting a true H0

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16
Q

What is a p-value?

A

The probability of getting a sample as extreme or more extreme as ours given that the null hypothesis is true

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17
Q

What is accuracy?

A

How close a measurement is to the true value intended to be measured

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18
Q

What is Precision?

A

How repeatable a measure is, irrespective of how close it is to the actual value

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19
Q

What is bias?

A

Systematic lack of accuracy

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20
Q

What is an experimental unit?

A

The physical entity which can be assigned to a treatment

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21
Q

What is a treatment group?

A

A group of experimental units that all receive the same treatment

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22
Q

What is an experimental factor?

A

A set of treatments and controls

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23
Q

What is replication?

A

The process of assigning several experimental units to the same treatment/intervention

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24
Q

What is independence and pseudoreplication?

A

Value of a measurement from one unit is not affected by the values of other units

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25
What is the standard error?
Precision of mean as an estimated parameter
26
What does standard deviation show?
Spread of data
27
What is a priori?
Knowledge considered to be true without investigation (like π=3.14)
28
What is the F-distribution?
Partition of variability
29
What is homoscedasticity?
Assumption of equal variances in different groups being compared
30
What is residual term?
The difference between the observed Y value and the fitted Y value for the same X
31
What are influential cases?
Extreme values that might influence the regression results when included or excluded from the analysis
32
What is a binary response?
A response or trait that takes on one of two possibilities
33
What are examples of sampling units?
Cohorts of patients Clusters of related genes Regions in tissues or genes
34
What are examples of experimental units?
Individual organisms Tissue culture plates
35
What is a control group?
Group used for comparison - not always needed
36
What is a feature of an experimental group?
Vary by only one variable Randomly sampled At least three replicas
37
What is an independent variable?
The one we change between groups
38
What is a dependent variable?
The one that changes in the experimental group as a result (Ie depends on another thing)
39
What is a controlled variable?
The one we keep constant
40
What is an experimental variable?
Actual property measured by the individual observation
41
What is a random variable?
Measured property whose results are not known before a sample is taken
42
What is falsificationism?
Hypotheses are there to be disproved because proof is logically impossible
43
What are the steps of a falsificationist test?
Observation of a pattern or a deviation from a pattern Explanation of an observed pattern is a model or a theory Predictions deduced from the model or theory Experimental tests
44
Practicalities to think about when asking questions in biology
Ethics Has the material been prepared in a way that doesnt affect outcome Can we study material of interest under Lab conditions Suitable experimental system Justifiable assumptions
45
What does hypothesis formulation depend on?
Systematic observation
46
What are the advantages of experimentation?
Reliable evidence to infer causality Distinguish between hypothesis Independently assess the effect of external factors on variables
47
What are the disadvantages of experimentation?
Experiments involve artificial manipulations that can be amplified by the laboratory environment The bigger space or time the thing occupies, the harder it is to experiment on Experiments are directly challenged by their natural variability Drawing general conclusions from experiments is not always possible
48
What should a set of units represent?
A sample of a clearly designed population - all the possible observations we are interested in
49
What are the types of numerical data?
Discrete (counts) and continuous (measurements)
50
What are the different types of categorical data?
Nominal (categories with no ranked order) Ordinal (Ranked/ ordered categories)
51
What is a sample space?
All potential values for a variable
52
What is external validity?
Can we generalise (from mice to humans)
53
What is internal validity?
Does the sample accurately reflect what is going on in the group we are studying
54
What is the difference between sample and population distribution?
Sample = the pattern the data makes Population = the pattern the whole group of interest makes
55
What does the area underneath a normal distribution curve represent?
The proportion of the population being that thing
56
What is the central limit theorem?
If you have a population with a mean and a standard deviation and take big enough random samples from the population, then the distribution of the sample means will be approx normally distributed
57
What is standard error of the mean?
How much uncertainty there is in the estimate of the population mean
58
What are confidence intervals calculated using?
The standard error of the mean
59
What are the main functions of graphs?
Exploration Analysis Presentation and communication of results Aid stats analysis
60
What do dot plots show?
Skewness and large or small values
61
Why are box plots useful?
Resistant to extreme values and show distribution
62
What can scatter plots identify?
Normality and linearity
63
What are the graph integrity principles?
Numbers depicted on the graph should be proportional to the numbers reported by the data Clear and complete labelling Show data variations not design variations Number of variable dimensions must not exceed the number of dimensions in the data Graphs must not quote data out of context
64
When do you use a t statistic?
When you don’t know the standard deviation and can assume normal distribution
65
What are the steps of the hypothesis test?
Formulate hypothesis Calculate test statistic Consider decision rule State decision rule Conclude and report
66
What is a decision rule?
T statistic or P value Something that tells us when to reject the null hypothesis
67
What is the difference between a database and a spreadsheet?
Database: meaningfully structured and stored, always electronic, Spreadsheet: interactive computer application, collection of a variable of interest aiming at answering a scientific question, table of variables with all observations of a variable of the same type
68
What are the sources of bias?
Non random sampling Conditioning of biological material Interference by the process of investigation Investigator bias
69
When do you have to use nonparametric tests?
When the sample size is small you dont know the distribution Cant assume data is normally distributed
70
Why do we use parametric tests where possible?
More informative and powerful than non-parametric tests
71
What does a sign test do?
Decides whether the data are equally likely to be on either side of a reference value
72
What are the assumptions of a sign test?
Ordinal, continuous dataset A set of independent measurements
73
What is the Wilcoxon signed rank test?
Rank of an observation amongst a set of observations
74
What does the Mann-Whitney-Wilcoxon test do?
Decide whether population distributions are identical without assuming normality
75
What does the random test measure?
Whether the observed data are different from a random distribution generated by reordering the observed data
76
What are the assumptions of the random test?
Observational independancy
77
What are the criticisms of the bonferroni correction?
General null hypotheses are rarely of interest Counterintuitive as interpretation depends on the number of tests
78
What is the purpose of ANOVA?
Comparing means across groups or factors
79
What does correlation measure?
Degree of a relationship between two variables
80
What is the parametric correlation test?
Pearson correlation coefficient
81
What are the assumptions of the Pearson correlation coefficient?
Variables must be normally distributed Relationship between them is assumed to be linear
82
What are the non-parametric correlation measures?
Spearman’s rank correlation coefficient Kendalls rank correlation tau
83
Why would you use Kendall’s rank over spearman’s?
Smaller values Less sensitive to potential errors P-values are more accurate with smaller sample sizes Better statistical properties Interpretation is very direct
84
What does simple linear regression investigate?
A linear association between an outcome and an independent variable
85
What are the types of regression diagnosis plots?
Residuals vs fitted Normal q-q Scale-location Residuals vs leverage
86
What is cooks distance used to find?
Influential outliers

Experimental Design And Data Analysis (1 decks)

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