Statistics in Allied Health Flashcards
1
Q
What is the purpose of statistics?
A
- control sources of variation; detect outliers
- analysis of data
- interpret the statistical and practical significance of results
- in making scientifically sound decisions and communicating them
2
Q
What are descriptive statistics?
A
- describe what was observed in the sample numerically or graphically
3
Q
What are some common numerical descriptors?
A
Mean and standard deviation for continuous data types (i.e. age)
4
Q
Frequency and percentages are useful for describing what data?
A
categorical data i.e. gender
5
Q
What is inferential statistics?
A
uses patterns in the sample to draw inferences about the population represented
6
Q
What are some examples of inferential statistics?
A
- Hypothesis testing: yes/no questions about the data
- Estimation: estimating numerical characteristics of data
- Correlation: describing associations within the data
- Regression analysis: modelling relationships with the data
7
Q
What can inferential stats be used for?
A
- forecasting, prediction and estimation of unobserved values either in or associated with population studies
8
Q
What is a sample as compared to a population?
A
- sample is a subset of the population
- population is a group of people with a common trait
9
Q
What is one of the most important factors of the sample?
A
It’s representation on behalf of the population as we use the sample to infer about the population.
10
Q
What are the two types of sample selections?
A
- probabilistic: everyone has a similar chance of being selected
- non-probabilistic: not everyone has the same chance of being selected
11
Q
What are some probabilistic sampling methods?
A
- simple/stratified random sampling
- systematic random sampling
12
Q
What are some non-probabilistic sampling methods?
A
- convenience sampling
- snowball sampling
- purposive sampling
13
Q
What are the 4 types of variables?
A
Nominal, ordinal, interval and ratio
14
Q
What is nominal data?
A
numbers given to a variable have no significance
15
Q
What is an example of nominal data?
A
0 = male, 1 = female
16
Q
What is a dichotomous variable?
A
a variable (nominal) with two possibilities
17
Q
What is ordinal data?
A
the order of the number holds significance
18
Q
Give an example of ordinal data
A
- pain scale
- likert scale
19
Q
What is interval data?
A
continuous variable, the value of 0 does not indicate the absence of a quality
20
Q
Give an example of interval data
A
temperature
21
Q
What is ratio data?
A
continuous variable where the value of 0 does indicate the absence of a quality
22
Q
What is an example of ratio data?
A
weight
23
Q
When is a continuous variable classified as discrete?
A
if it is restricted to a fixed number of values
24
Q
What is raw data?
A
value the same unit as it was measured in
25
What is scaled data?
units of measurement given a relative value that makes it comparable to other values in the general population
26
What is the criterion variable/outcome variable?
The presumed effect in a study
27
What is the predictor variable/covaraite
The presumed cause in a experimental study (potentially associated with the outcome variable)
28
What is relative frequency?
The frequency in a subgroup relative to the total number
29
What are mutually exclusive variables?
Variables that don't overlap
30
What is a example of a mutually exclusive variable?
age
31
What data does bar graphs show?
crude data not relative data
32
What data does pie graphs show?
can show both crude and relative data
33
What do scatter plots show?
correlation between two continuous variables simultaneously
34
What do line graphs show?
time trends where the x axis shows the unit of time and the y axis displays the values of the variable being plotted
35
What do histograms show?
differences in frequencies or percentages among categories of continuous variables
36
In a histogram, what is the 1) width of the bars 2) height of the bars proportional to?
1) width of the category
| 2) frequency of percentage of that category
37
What does the histogram present?
distribution of data, gives an estimate of the probability distribution of continuous variable. Shows how skewed/shifted data is
38
In a histogram, if the data is left tailed what does it mean?
negative skew
39
In a histogram, if the data is right tailed what does it mean?
positive skew
40
What does a box plot body represent?
the first to third quartile
41
How are outliers plotted in a box plot?
separately as positions on the chart
42
What is the line in the box plot body?
median of data set
43
What are the whiskers in a blot plot represent?
bottom whisker - Quartile 1 to lowest non-outlier
| top whisker - Quartile 3 to largest non-outlier
44
What are some measures used in quantitative research?
- counts i.e. number of patients
- proportion: relative frequency, must be divided by the total number in the group
- rates: used to involve or imply a relationship
- measures of central tendency: measures that best represents the data
45
What are some measures of central tendency?
- mean
- median
- mode
46
How is the mean calculated?
add all observations and divide by number of observatios
47
What is the mean effected by?
In repeated measures but is easily effected by extreme values
48
What is the median
The middle value i.e. 50% of data above and below the median
49
Is the median effected by extreme values?
no
50
What is the mode?
most commonly occurring value
51
Is the mode effected by extremes?
no
52
What are measures of variability?
Inform of the spread of the ata
53
What are some measures of variability?
standard deviation, range and interquartile range
54
What is variance?
average of the squared differences of each of the observations from their mean
55
What does a low and high standard deviation mean?
- low: little spread of data
| - high: large spread of data
56
What must the sum of deviations around the mean equal?
0
57
What is the normal distribution?
a curve that is bell-shaped and symmetrical around the mean
58
What is the area under a bell-curve equal to?
1
59
In normal distribution, what values are equal?
mean, median and mode
60
How many values lie 1 standard deviation away from the mean?
68%
61
How many values lie 1.96 standard deviations away from the mean?
95%
62
How many values lie 2.58 standard deviations away from the mean?
99%
63
What is the confidence interval?
limits within which the true population probably lies. Gives a range of values that may reasonably contain the true population parameter
64
What are the parameters of the confidence interval?
lowest value (lower confidence limit) and highest value (upper confidence limit)
65
What is the 95% confidence interval?
the range of scores or values in which it is 95% confident that the true population mean lies
66
What is a null hypothesis?
A is similar to B or A is not different to B
67
What is alternative hypothesis?
A is different from B or A is larger/smaller than B (there is a relationship between variables)
68
What is a type 1 error?
when we reject the null hypothesis when it's true
69
What is a type 2 error?
when we accept the null hypothesis when it's not true
70
What is the power?
the probability of rejecting the null hypothesis when it's false
71
What is the P value?
significance of comparison
72
What does a P value smaller than 0.05 mean?
researcher is confident enough the reject the null hypothesis and accept alternative hypothesis
73
What can a P value tell us?
observed difference between compared measures could have been obtained by chance alone
74
How can nominal data be analysed?
non-parametric statistic techniques i.e. counting individuals in groups
75
What are some weaknesses of ordinal scales?
may be subjective - terms need to be clearly defined
76
How can ordinal data be analysed?
non-parametric statistic techniques
77
What are the continuous variables?
interval and ratio data
78
How can interval and ratio data be analysed?
parametric statistical techniques
79
What is an accurate measure?
One which close to true population value
80
What is a precise measure?
one which yields close to the same value with many repetitions
81
Where does systematic error arise from?
measuring, collecting, analyzing and interpreting data
82
What does a CI of 90% mean?
90% sure the patient' true score lies within a determined range
83
What does a P values of >0.05 indicate?
results were chance findings
84
What do percentiles indicate?
how many lie above and below the score
85
What are the quartiles?
1st quartile: 25th percentile
2nd quartile: 50th percentile
3rd quartile: 75th percentile
86
What are the deciles?
First Decile: 10th percentile
| Second decile: 20th percentile etc.
