QM #2 - #4
The normal distribution &
null hypothesis-testing
Populations & Samples
Populations
💡 The collection of units to which we want to generalize a set of findings or a statistical model
📝 people, plankton, plants, cities, suicidal authors, etc.
Samples
💡 A smaller (but hopefully representative) collection of units from a population used to determine truths about that population
Calculating "error"
Standard
deviation (SD)
💡 A quantity expressing by how much the members of a group differ from the mean value for the group.
Mean
Sum of Squared
Errors (SS)
💡 The sum of different deviations
SS, variance, & SD represent the same thing
Error 😖
How well the mean represents the observed data 🙆🏻
The variability
in the data
The ‘fit’ of the mean
to the data
Variance
💡
Standard
error (SE)
💡 the standard deviation
of the sample means
Test Statistic
💡 A statistic for which the frequency of particular values is known
💡 a simple statistical model of the centre of a distribution of scores
Probability
💡 A quantitative statement of the likelihood of occurrence of an event
Statistic &
lang. research
Descriptive
statistic
Inferential
statistic
💡 used to display, summarise & describe data
🗝 Mean, standard
deviation, & range
💡 used to
interpret the data
🗝 a statistical test that tests a prediction
📝 statistical test
χ2 (“chi-square”)
t-test
Analysis of Variance (ANOVA)
correlation
Dependent
Independent
Data
patterns
Distribution
💡 the pattern of values in a set of observation
Measures of
central tendency
💡 measure representing the centre or middle of a distribution
Measures of dispersion
💡 reflect spread of values (scores, measures, etc.) in a distribution
Mode
💡 Most frequently occurring scores
Mean
💡 Arithmetic
average of score
📝 bi/trimodal
Normal distribution
💡 A symmetric, 🔔-shaped probability distribution, used as the theoretical model for the distribution of physical and psychological variables
Involved many observations
Percentage &
percentiles
💡 Percentiles indicates the location of a score
in a distribution (in %) > where
📢 % of the data that is below the amount in ❓
📢 % of the data that is at or below the amount in ❓
Standard scores
(z scores)
💡 how many SD away from the mean
📝 https://www.youtube.com/watch
?v=mDJvDRvvDXo
🛠 Function
💑 among
observations 👓
possible
sources
Systematic
factors
Chance
Systematic factors
➕ Chance
Logic of experimental research
Cause and Effect
💡 contiguity
Confounding
variable
💡 The 3rd factor that cause confusion on the result of a research
📝 The 💑 between breast implants & 💀 is confounded by self esteem
Comparing an individual score in relation to the group
Locating a
data in a distribution
Null hypothesis-testing
💡 An attempt to reject a purely chance explanation
Rejecting a NH supporting our research
No theory can
be proved
Confirm / support a theory
Dis-confirm
Formula: test score - mean / SD