PAS Flashcards
What does significant mean?
Sufficiently great or important enough to be worthy of attention
What do you have to do to show an effect is clinically significant?
Show the effect is big enough to matter
What is the effect size?
Distance between the treated and control samples
What is real effect size?
Treated mean- control mean
What does s.e.m mean?
Standard error of the mean
What is s.e.m?
Measure of confidence in the experimental result
What does induction mean?
Inference of a generalised conclusion from particular instances
What is a synonym for numerical variables?
Quantitative
What are numerical variables?
When the values are numerical or can be represented with numbers
What is continuous quantitative data?
Take any value within a range
What are discrete quantitative data?
Specific points on a scale - normally whole numbers
What is a qualitative variable?
Variables whose values are not numerical (categories, labels or groups)
What are the three types of qualitative variable?
Nominal, ordinal and dichotomous
What is a nominal variable?
No natural order
What is an ordinal variable?
Natural order
What is a dichotomous variable?
Only 2 options
What does a column chart show?
Comparison among different items
When is a bar chart used?
Horizontal column chart, when the item data labels are too long or you have too many items to compare
What does a line graph show?
A trend or progress over time
What does a pie chart show?
How categories represent part of a whole
What does a stacked bar chart do?
Compare many different items and show their comparison
What is another name for a mekko chart?
Mosaic chart
What does a mekko chart show?
Compares values, measures their composition and shows how the data is distributed across each one
What is an area chart?
Line chart where the x axis and line is filled with a colour or pattern
What is an area chart useful to show?
Part-whole relationships
What does a dual axis chart show?
Plot three data sets with one shared axis
What is a dot plot?
Visual idea of the spread of data points
What does a histogram present?
Numeric data and its frequency distribution
What is a box and whisker plot?
Statistical summary of a set of data
What does a scatter plot do?
Demonstrates distribution
What does a heat map do/show?
The relationship between two items and provides rating info displayed as a colour or saturation
What is Normal distribution?
Mathematical model that describes how data clusters around the mean and reduces the further away you go
What are the characteristics of a normal distribution curve?
- area under the curve is the total probability and will always add up to 1 (or 100%)
- peak = mean
- curve is symmetrical
What does standard deviation characterise?
How short/tall the normal distribution curve is
What is the population?
The collection of individuals or data points
What is a sample?
Smaller group drawn from the population
What are the types of sample (8)?
Random, systematic, stratified, clustered, convenience, quota, purposive, snowball
What is a random sample?
Chosen entirely by chance
What is a systematic sample?
Selected at regular intervals
What is a stratified sample?
Divided into subgroups that share a characteristic first
What is a clustered sample?
A subgroup used for a sample
What is a convenience sample?
First volunteers through the door past a threshold
What is a quota sample?
You need a set number of each group
What is a purposive sample?
Relies on the judgement of the collector
What is a snowball sample?
One chosen person, who recruits the next person etc etc
What is the central limit theorem?
If a sample size is large enough then the sampling distribution of the mean is normal distribution
What is an inference?
Drawing a conclusion about a population from the sample we have
What is the null hypothesis?
Predicting the data wont show anything new (no change)
What is the alternate hypothesis?
Claims the parameter of interest falls within an alternative range of values
What does it mean if the null hypothesis is true?
No real effect
Can you accept the alternate hypothesis?
No, you have to reject the null hypothesis
What is a type 1 error?
If you think the data showed something important but really it happened due to chance (false positive)
What is type 2 error?
When you fail to reject a null hypothesis when you should have (false negative)
What is the critical value?
The point along the x axis at which you decide to reject the null hypothesis
When can you use error bars?
If you have three or more experimental replicates
What does the t test do?
Compares the means of two groups and checks if they are reliably different
What are the assumptions and criteria of the t test?
The data needs to be normally distributed and you have to have approximately equal numbers in all the samples
What does the null hypothesis in the t test assume?
The two means are the same
What does a two tailed t test allow for?
The possibility that the test stat is either very large or very small
What is a trend line?
The line that has the least amount of distance from each data point
What doesn’t the trend line tell you?
How well the points fit along the line
What is a Pearson’s R test?
How strong the correlation is and in what direction
