Introduction to statistical reasoning Flashcards
What is meant by theories and hypotheses being in the conceptual domain?
You cannot observe them directly
Explain why a hypothesis is not simply a prediction
An explanatory statement about something that is not yet observable. The prediction is not the hypothesis, it is something derived from the hypothesis that operationalises it so that you can observe things that let you determine the plausibility of the hypothesis
Give other words for predictor and outcome variables
Predictor- independent
outcome- dependent
What is meant by a nominal variable?
A variable made up of different categories
What is an ordinal variable?
The categories are put in a certain order (concentrations of a liquid)
What is interval data?
Numerical data given in intervals where each equal interval on the scale represents equal differences in the quality being measured (likert scale)
How does ratio data differ from interval data ?
the ratios of the values along the scale should be meaningful. For this to be true the scale must have a true and meaningful 0 point ( 2 should be half as effective as 1 when rating a product)
What is meant by a continuous variable?
A variable that can be measured to any level of precision
What is meant by criterion validity?
Whether you can establish that an instrument measures what it claims to measure through comparison to objective criteria
What is a within subject design?
When the same subjects are all given the various conditions
What is a between subjects design?
Different subjects take part in each condition
How can carry on effects of a repeated-measures design be negated
Counter-balancing the order the conditions come in
What does it mean for a graph to be positively skewed?
Skewed to the right
What is meant by kurtosis?
The degree to which scores cluster at the end of the ends of the distribution
What would it mean for a graph to have a positive or negative kurtosis?
Positive- many score at the tails and is pointy
negative-relatively thin in the tails and tends to be flatter than normal
What other names are given to graphs with negative and positive kurtosis?
Positive- leptokurtic
Negative-Platykurtic
What are the values of skew and kurtosis in a normal distribution?
0
Find the dispersion of this data set
12, 36, 37, 48, 56, 72
72- 12 = 60
Also known as the range
When there is extreme outliers what is done with the range?
Interquartile range- chop off the outside 25% both sides
Give another name for the second quartile
Median
Where is the second and third quartile located?
Middle of lower and upper halves of the data
What are quantiles?
Values that split the data in equal portions
What are the APA guidelines when deciding how to present your data? (4)
> Choose a mode of presentation that optimises the understanding of the data
3 or fewer numbers try use a sentence
4 and 20 consider a table
20 and above a graph is usually more useful
But use common sense
How many decimal places should usually be utilised?
As few as possible ( m, cm, mm example ) but maintain accuracy
