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Second Year Biology Semester 2 > Research methods > Flashcards

Research methods Flashcards

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1
Q

What is a fact in a scientific context

A

generally accepted reality based on objective inferences, verifiable by evidence that is published and accepted via peer review and replicated over time. Can still be open to scientific enquiry

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2
Q

Define the steps of the scientific method

A

1 - develop and define the problem (observation)
2 - formulate hypothesis
3 - gather data
4 - analyse and interpret results (test)

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3
Q

What are the two types of hypotheses

A

Null hypothesis - no relationship between variables
Alternative hypothesis - there is a relationship between anxiety

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4
Q

What are the 2 kinds of statistics

A

Descriptive statistics and inferential statistics

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5
Q

What is a hypothesis

A

A statement about some real-world
phenomenon that can be tested through
observations.

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6
Q

what is an independent variable

A

the factor you will be testing. Thing you will change (eg temp, conc etc)

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7
Q

What is the dependent variable

A

the effect you think will change and the thing you measure - is effected by independent variable

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8
Q

What must the hypothesis include

A

Must state the question you are asking as well as include both dependent and independent variables.

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9
Q

How many relationships should be included in hypothesis

A

1

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10
Q

What do you need to check about hypothesis

A

make sure its testable

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11
Q

What does APPEAR stand for

A

Acquire
Process
Plot
Examine
Analyse
Report

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12
Q

Describe Acquire (APPEAR)

A

Acquire data through sampling.
Need to decide how you do it, think about assumptions, ethical considerations, numbers, resources available.

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13
Q

What are some assumptions you have to make when sampling a population

A

that pop. is normally distributed, that you are randomly sampling

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14
Q

What is a T-test

A

used to test hypotheses about means when the population variance is unknown (usual)

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15
Q

What sample size do you want

A

as large as possible - will give more accurate data

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16
Q

What is a single sample T-test

A

when we only have 1 group that we want to test against a hypothetical

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17
Q

What is an independent samples T-test

A

We have 2 means and 2 groups that have no relation between each other

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18
Q

What are the 3 varieties of T-Tests

A

Single sample, independent samples and dependent samples

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19
Q

What is a pooled average

A

A weighted average of the two sample variances with weighting done according to sample size

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20
Q

What is a dependent T-test

A

2 means that are related to each other

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21
Q

when do we use t tests

A

when population variance is unknown and sample size is small (usually under 100)

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22
Q

What is an ANOVA test

A

(AN)alysis Of (VA)riance
A statistical test for comparing means between more than 2 groups

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23
Q

What does the F-test test

A

the hypothesis that two variances are equal. Will be close to 1 if variances are equal

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24
Q

what function do you use in R to import your dataset

A

read.csv()
e.g. Dataset1 <- read.csv(“dataset1.csv”, header = TRUE)

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25
Q

what is the Shapiro Wilks test

A

a normality test for a null hypothesis to check that results are normally distributed
if p>0.05 we fail to reject null hypothesis

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26
Q

What is the Bartlett test

A

Tests if there is a difference in variance between multiple sets of data
p>0.05 there is no difference in variance

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27
Q

what does it mean if shapiro test and bartlett test give p>0.05

A

data is normal with homogenous variance and therefor you can proceed with t test to analyse data

28
Q

what is a 1 sample t test

A

tests whether the mean of a single sample is significantly different from known or hypothesized mean

29
Q

what is a 2 sample t test (aka independent sample test)

A

used when comparing the means of two independent groups or populations and assesses whether the difference in means between the two groups is statistically significant

30
Q

what is a paired sample t test

A

used when comparing the means of two related groups or when each data point is paired. Determines whether the is a significant difference in the means

31
Q

what is a Post hoc test

A

used when ANOVA indicates significant differences and can identify which group differs from others

32
Q

What must you do before an ANOVA test

A

Must make sure data is normally distributed using Shapiro-Wilkes tests

33
Q

Name an example of a Post hoc

A

Tukey’s HSD (Honestly Significant Difference test)

34
Q

How do you interpret the results of an ANOVA test

A

if the p value (Pr(>f)) is less that 0.05 you can reject null hypothesis. This indicates that at least one group is significantly different from the others. Yu can use Post-hoc now

35
Q

What is the ANOVA function in R

A

ExampleA <- aov(dependent variable ~ independent variable, data = ANOVA1)

36
Q

What is a 2 way ANOVA test

A

used to investigate the effects of two categorical independent variables on a continuously dependent variable

37
Q

what is the Wilcoxon test

A

non-parametric rank test for statistical hypothesis testing used either to test the location of a population based on a sample of data, or to compare the locations of two populations using two matched samples

38
Q

what needs to be checked before a two way ANOVA

A

Check groups are independent
Normality (shapiro test)
Homogeneity (Barlett test)

39
Q

what are regression models

A

a relationship between one dependent variable and explanatory variables. They are used mainly for prediction and estimation

40
Q

How do you set up relationships in regression models

A

Use equations - numerical dependent variables and 1 or more numerical or categorical independent (explanatory) variable

41
Q

What are the steps of regression modeling

A

Hypothesize relationship between variables
Specify probability distribution of random error term
Evaluate the fitted model
Use the model for prediction and estimation

42
Q

What is model specification based on

A

Theory - theory of field, mathematical theory, previous research and common sense

43
Q

what are the two main types of linear regression and when are they used

A

simple linear regression when you have only one independent variable
multiple linear regression which uses two or more independent variables

44
Q

How do you interpret the results of regression

A

by using summary function summary(model) which provides detailed output including coefficients, r squared p values and more

45
Q

What are co-efficients (linear regression0)

A

The intercept and coefficients of independent variables

46
Q

What is R-squared (linear regression)

A

this value measures the models goodness of fit and represents the proportion of the variance in the dependent variable

47
Q

what is the p value (linear regression)

A

a low p value (<0.05) for the independent variable(s) suggests a significant relationship between variables

48
Q

why are boxplots important

A

they are essential for visualising and summarising data. They provide a quick way to assess distribution of data and identify outliers

49
Q

what is a boxplot

A

a graphical representation of the distribution of a dataset.
It displays a 5 number summary of a set of data

50
Q

What are the 5 main points of a boxplot

A

the minimum, first quartile, median, third quartile and maximum

51
Q

Describe the ‘anatomy’ of a boxplot

A

The box itself is the interquartile range and spans from q1 - q3 with the median (q3) inside
The lines on either side extend to the maximum and minimum values with 1.5x the IQR.
Anything out with this are the outliers

52
Q

Why use boxplots

A

makes it easy to identify skewness, central tendency and spread in data
good for visualizing non normal distribution
helps spot outliers
easy to compare

53
Q

How do you create a boxplot

A

Order the data
Calculate the quartiles
Determine the IQR (Q3-Q1)
Find upper and lower limits
Identify outliers
Plot boxplot

54
Q

Give some examples of non parametric tests

A

The Wilcoxon test and the Mann-Whitney U test

55
Q

How do you interpret a boxplot

A

The median represents the centre of the data distribution whilst the box length represents the spread of the middle 50% of the data. The whiskers show the range of most of the data and outliers can be identified as individual points outside the whiskers

56
Q

what extra information does a parametric test use

A

they operate under the assumption that the data is normally distributed

57
Q

Give some examples of parametric tests

A

t tests, anova

58
Q

what is nonparametric data

A

A class of statistical procedure that do not rely on assumptions about the shape or form of the probability distribution from which the data were drawn

59
Q

What are the advantages of nonparametric tests

A

You can use these tests with any numeric variables with any distribution

60
Q

What are the advantages of parametric tests

A

they use more information from available data which allows for more confidence of ruling out chance and finding real differences

61
Q

why do we not always use parametric tests

A

data has to be normally distributed, interval or ratio level, and variance must be similar

62
Q

what is the chi squared test

A

A method suited for situations involving larger sample sizes where it provides reliable insights into the independence or association between categorical variables

63
Q

TRUE OR FALSE: if all conditions are met you should use parametric tests over non parametric tests

A

TRUE

64
Q

what is the Wilcoxon test

A

non-parametric rank test for statistical hypothesis testing used either to test the location of a population based on a sample of data, or to compare the locations of two populations using two matched samples

65
Q

What is the Fisher’s exact tests

A

useful in smaller sample sizes or when dealing with 2x2 contingency tables where expected cell counts are low
It computes the exact probability of obtaining observed distribution

66
Q

What is the Mann Whitney U test

A

Similar to Wilcoxon test but for independent samples

Second Year Biology Semester 2 (4 decks)

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