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CVDM > Statistics > Flashcards

Statistics Flashcards

1
Q

What is population/global data?

A

A huge dataset to be investigated, or an experimental set of data within a specific condition

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2
Q

What is sample data?

A

A small set of data from the population/global data

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3
Q

What is sampling?

A

Randomly taking samples from the population

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4
Q

What is mean?

A

The sum of all sample values divided by the number of samples

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5
Q

What is standard deviation?

A

Gives the average distance of the samples from the mean

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6
Q

How is standard deviation calculated?

A

Square root of the (sum of the distances from the mean) divided by the number of samples -1

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7
Q

What is frequency?

A

How often many similar data occurs/happens

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8
Q

What is distribution?

A

The shape constructed by data frequencies

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9
Q

True or false:
A histogram can show frequency?

A

True

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10
Q

What type of curve can be plotted on a histogram?

A

A normal distribution curve

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11
Q

What is normal distribution?

A

A range in which there is most data in the middle and less data at either ends of a curve. It is symmetrical around the mean. It shows that data near the mean are more frequent in occurrence compared to data far from the mean

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12
Q

What does variable view in SPSS show?

A

The name of the variable
The type of data the variable is
A label to describe the variable

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13
Q

Three data types in statistics

A

Numeric data
Nominal data
Ordinal data

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14
Q

What is numeric data?

A

Numbers
e.g. body mass, weight, stature

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15
Q

What is nominal data

A

Category data without rank
e.g. gender

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16
Q

What is ordinal data?

A

Categories with rank
e.g. feeling

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17
Q

What does data format in SPSS allow?

A

Subject information to be entered

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18
Q

What is the standard error of the mean?

A

The standard deviation of means.
Shows the range in which a global mean could fall

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19
Q

How is standard error of the mean calculated?

A

Standard deviation divided by the square root of n

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20
Q

In what percentage of means is mean+/- 1SE?

A

68-70% of means

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21
Q

In what percentage of means is mean +/- 2SE?

A

95% of means

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22
Q

In what percentage of means is mean +/- 3SE?

A

99% of means

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23
Q

What mean +/- SE is indicative of population mean?

A

Mean +/- 2 standard error - 95%

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24
Q

What is the confidence interval?

A

The range in which the global mean could be within

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25
Q

What is a 95% confidence interval?

A

Mean +/- 2 standard error

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26
Q

What is the median?

A

The middle value of the sample data

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27
Q

What are quartiles?

A

The sample values at 25%, 50% and 75%

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28
Q

What can a simple bar diagram be used for?

A

Counting number of cases
Showing percentages of cases
Showing two variables together

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29
Q

What does a pie plot show?

A

The percentage of data

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30
Q

What does the box plot show?

A

The median, quartiles and extreme values within a category

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31
Q

What does an error bar show?

A

Shows the mean and the 95% confidence interval or SD of the data

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32
Q

What does a scatter/dot diagram show?

A

Shows the tendency of the data or the relationship between variables

33
Q

What is independent sample data?

A

When the measurements have no effect on each other

34
Q

What is dependent sample data?

A

When the measurements have an effect on each other

35
Q

True or false:
Whether the data is dependent or independent depends on the subjects

A

False - it depends on the experimental situation

36
Q

Why do we need a reasonable sample size?

A

Fewer samples could result in a larger difference between the local and global population

37
Q

What is statistical power?

A

The likelihood of a significance test detecting an effect when there actually is one

38
Q

How is population mean range calculated?

A

Mean +/- 2 SEM

39
Q

What does the letter W represent in statistics?

A

The difference between population means

40
Q

What is subjective data?

A

Information that comes from opinions, feelings, perceptions etc

41
Q

What is objective data?

A

Results produced from measurements

42
Q

3 ways to determine whether the data is normal distribution

A

Skewness coefficient
P-P plot
Kolmogorov-Smirnov test

43
Q

What is skewness coefficient?

A

A measure of the asymmetry of a distribution

44
Q

True or false:
Between 2 sets of sample data the mean is sometimes the same?

A

False - the mean will never be the same

45
Q

What is a T-test?

A

A parametric test where t is a parameter used to analyse data with normal distribution or similar to normal distribution

46
Q

True or false:
The samples should be in normal distribution for T-test to be applied

A

True

47
Q

What does a T-test do?

A

Examines if two means are significantly different, therefore requires two groups of data

48
Q

What is a paired-sample T-test?

A

When there is two measurements for each subject

49
Q

What is an independent T-test?

A

It compares the means of two independent groups

50
Q

What test is used for testing for differences among multiple groups of data?

A

ANOVA

51
Q

What is variance?

A

A descriptor to show how far away samples are from the data centre

52
Q

What are the two variances?

A

The variance within group shows difference between samples
The variance between groups shows differences between groups

53
Q

What shows the variance between groups?

A

The distances between the group means and the total mean

54
Q

What indicates the variance within a group?

A

The size/diameter of a cycle/group

55
Q

What are the two squared differences?

A

Between the group mean and the total mean
Between the samples and the group mean

56
Q

What does ANOVA do?

A

Uses the F value to see if there are differences between groups

57
Q

One-way ANOVA:
What is it?
What are the conditions?
What is the applied situation?

A

It is an extended t-test for comparing multiple groups of data together
It requires an independent factor and a quantitative dependent variable
The applied situation is in multi-group data

58
Q

True or false:
For ANOVA, the data should be in normal distribution or similar to normal distribution

A

True

59
Q

What does a Chi squared test do?

A

Compares the observed and expected frequencies in each category to test if all categories contain the similar proportions of values
Tests whether there is significant differences between groups

60
Q

Examples of non-numeric data

A

Score system
Pain
Treatment type
Equipment type

61
Q

What do non-parametric tests do?

A

Directly use non-numeric information from data to compare sample groups

62
Q

What is the Wilcoxon signed-ranks method?

A

It has the null hypothesis that two related medians are similar
Allows us to compare a single median against a known value or two medians from the same individual group

63
Q

What is Mann-Whitney test used for?

A

To compare two independent groups
Suitable for non-numeric data
Uses rank information

64
Q

What is a scatter dot graph used to show?

A

Whether or not two variables are correlated
Shows trend and pattern

65
Q

What is the correlation coefficient?

A

Used to describe whether two variables have a linear relationship and how strong the relationship is
It measures how variables are linearly related

66
Q

The closer to/further from 1, the stronger the correlation between variables

A

Closer to 1

67
Q

What does R>0 mean?

A

A variable increases while another variable increases

68
Q

What does R<0 mean?

A

A variable increases when another variable decreases

69
Q

What value is indicative of valuables having a linear relationship?

A

xxx <0.05

70
Q

What is linear regression?

A

It is used to construct an equation to describe the relationship between two, or multiple, variables

71
Q

What are residuals?

A

The sum of the squares of differences between the predicted and practical values

72
Q

How can we use linear regression in variables that are not linear?

A

By transforming them into a suitable form by using a linear coefficient

73
Q

What is survival analysis?

A

Initially used to analyse how death ratios changed with ages
Can now be used to analyse effect of medical therapies e.g. implants

74
Q

What are censored cases?

A

Cases from which data cannot be collected or determined by their situations for some reason not related to the factor studied

75
Q

What is meta-analysis

A

A method to use multi-source data to analyse the favourite by most of the studies

76
Q

Why is it good to carry out meta-analysis?

A

Many studies have their own attitudes, report only the differences, and give different conclusions/opinions

77
Q

Steps for meta-analysis

A

Select a factor
Collect data from multiple sources
Calculate parameters
Make a forest plot
Give conclusions

78
Q

What is the odds ratio?

A

The proportion of the number of cases to the number of non-cases

79
Q

What is the relative ratio?

A

The number of cases with the event compared to the number of samples

CVDM (16 decks)

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