WEEK 1 (GALTON + NORMAL DISTRIBUTION)
Who is Galton's famous cousin?
Charles Darwin
Define Alpha Level?
-Arbitrary
-Psychological standard
-Threshold value to judge whether a test is statistically significant
-Ranges from 0 to 1
Define Reliability + Validity?
Reliability: Stability of a given measure (measure of consistency, e.g. weight/height)
Validity: The degree to which a measure measures what it claims to measure
What is a Z-Score?
-Also known as ‘Standard Score’
-Tells us where a score lies in relation to the mean (using standard deviations)
-Can be positive or negative
What is a P Value?
-Arbitrary
-Psychological standard
-Threshold value to judge whether a test is statistically significant
-Ranges from 0 to 1
What are the 4 steps of the Research Process?
1. Research Question
2. Research Design
3. Findings/Answers
4. Share/Publish Findings
What are Galton's 3 elements of Probability?
RANDOM EXPERIMENT
POSSIBLE OUTCOMES
PROBABILITY ASSIGNED TO OUTCOMES
How did Fischer view Populations?
ABSTRACTIONS NOT REALITY
VALUES (NOT INDIVIDUALS)
FREQUENTISM (LONG RUN)
SAMPLES: ALL VALUES ARE RANDOM SAMPLES (can calculate to probability of any value, if we observe the characteristics of any population)
The Independent Variable is the cause. Its value is independent of other variables in your study.
The Dependent Variable is the effect. Its value depends on changes in the independent variable.
What are Galton's Goals of Statistics?
COLLECTING LARGE SAMPLES TO UNDERSTAND POPULATIONS + provide a summary of collected data
Summaries = distributions, means, standard deviations
Statistical methods = Regression + correlation coefficient
What is Null Hypothesis Significance Testing?
-Never proven, only possibly rejected
-The goal of an experiment gives facts a chance to disprove this
-An alternative is ineligible (inexact)
What are 3 Sampling issues?
Non-response bias (systematic difference between those who took part in a study + those who did)
Volunteer subject problem (people tend who volunteer for studies differ from normal population via demographic characteristics)
'College sophomore problem' (majority of psychology studies are based on uni students as participants)
What are the 5 characteristics of Normal Distribution?
Possible values are in the interval from negative infinity to positive infinity
Distribution is symmetric + centered in the mean of the distribution
Mean equals the median: Observing a value in the interval values above + below the mean has a PROBABILITY OF 0.5
Z scores: calculated by subtracting the mean from raw values + dividing that result by the standard deviation
A normal distribution of z scores = STANDARD NORMAL DISTRIBUTION (mean of the SND is always 0 + standard deviation is always 1)
How did Fischer view Statistical Variation?
INTERESTING IN ITSELF (NOT ERROR)
FREQUENCY DISTRIBUTIONS (TO COLLECT DATA, YOU OBSERVE VALUES + THOSE VALUES ARE DISTRIBUTED IN CERTAIN WAYS. THE MORE/LESS YOU OBSERVE VALUES IN SOME INTERVAL ETC.)
What are 2 advantages + disadvantages of Self Report Measures?
Advantages?
Cheap + easy to administer
First-hand experience from participants
Disadvantages?
Social desirability concerns (respondents give answers that make them look good)
Potential demand characteristics (any cue that makes participants aware of what the experimenter expects)
Possible retrospective bias (where participants view/interpret past events as inaccurate)