SPSS Flashcards
What is a continuous variable?
Arising from measurements (e.g. height)
What is a discrete variable?
Arising from counting (e.g. number of books on a bookshelf)
What is a nominal/categorical variable?
Having no natural order
What is an ordinal variable?
Having natural order
What is simple random sampling?
NPS: Each member of the population has equal chance of being selected.
What is systematic sampling?
NPS: Every nth subject from a population list is chosen
What is stratified random sampling?
NPS: The population is split into groups of similar individuals from which a sample is drawn
What is disproportionate sampling?
NPS: If strata in population are of substantially unequal size
What is Cluster sampling?
NPS: Successive random sampling a series of units in a population.
What is convenience sampling?
PS: Samples are based on availability
What is quota sampling?
Researcher guides sampling process until participant quota is met (e.g. volunteers called for until equal quota of males/females is met)
What is purposive sampling?
Subjects are hand picked based on certain criteria
What is snowball sampling?
Used when desired characteristics are rare. Initial subjects refer others with similar characteristics
What happens to your accuracy if you quadruple your sample size?
It doubles
Name 7 types of Experimental designs
RCT, Blind study, Cross over design (each subject has own control but order of treatments is randomised), Factorial design (several factors compared at once), outcome variables, Quasi experimental design (Often happens when independent variable in question is an innate characteristic of the participants involved), single subject study
Name 9 types of observational designs
Retrospective, prospective, surveys and polls, observation, longitudinal cohort studies, case-controlled study, cross sectional study, case reports, questionnaires.
What is dichotomous survey questioning?
Two possible answers - yes/no/agree/disagree
What is likert scale in surveys?
3-5 categories of responses usually provided
What is visual analogue scale in survey?
Results measured along a continuum
Why can histograms be subjective?
Dependent on number of bins
What is the interquartile range?
Minimum = 1st quartile 0.25 = 2nd quartile Median = 3rd quartile 0.75= 4th quartile Maximum = 5th quartile
Which chart/graph best displays the interquartile range?
Boxplots
What type of data best suits bar chart?
Categorical variables
What is the standard deviation
How far away values deviate from the mean
What is the formula for degrees of freedom
n-1
What is the standard error?
How far the sample mean deviates from the population mean
What is a parameter?
A numerical characteristic of a population
What is a statistic?
A numerical characteristic of a sample (e.g. mean, SD)
What are the confidence intervals associated with a normal distribution?
68% of values within 1 SD of the mean
95% of values within 2 SD of the mean
99.7% of values within 3 SD of the mean
What is the central limit theorem?
The Central Limit Theorem states that the sampling distribution of the sampling means approaches a normal distribution as the sample size gets bigger- no matter what the shape of the population distribution
What is a Type 1 Error?
Null hypothesis is rejected when it is actually true (False positive)
What is the relationship between Type 1 Error and the P-Value?
The probability of making a type 1 error is precisely the significance level we set our p-Value at
What is a Type II Error?
Where we don’t reject the Null hypothesis and we should have
What is Power?
The probability of detecting an effect when there is indeed an affect
How can power be improved?
Decreasing effect size, decreasing variability, Increasing sample size, decreasing the significance threshold (but this can increase Type I Error)
What is a Parametric test?
Tests some parameter in your population
What is a Non-Parametric Test?
Looks at some comparison between groups, such as comparing the “ranks” of values instead of the values themselves.
What are the three Parametric test assumptions?
- Normality: Data have normal distribution
- Homogeneity of variances: Data from multiple groups have the same variance
- Independence: Data are independent
What does a p-Value of <0.05 for Levene’s test tell you?
That the Variances are not equal and a parametric test cannot be performed.
What does a p-Value of >0.05 for Levene’s test tell you?
That there is less than 5% chance that the equality in the variances occurred by chance.