Methods in Psychology (Chapter 2) Flashcards
Range
Difference between the highest and lowest scores in a distribution
Measure of central tendency
Summarizes data - single score that represents a whole set of scores
Mean
Average of score
Median
Middle score, half of scores are above it and half below.
Mode
Most frequently occurring score
Standard deviatoin
Computed measure of how much scores vary around the mean score
Longitudinal Study
Study the same cohort over time
Cohort
group of people who share similar characteristics or experience
Cross-sectional study
study of people in different cohorts at the same point in time
negative r variable
negative correlation (less is more)
positive r variable
positive correlation (more is more)
r variable = 0
little to no correlation
Descriptive statistics
Used to summarize, organize, characterize
Descriptive statistics include…
Central tendency, correlation, variability
Inferential statistics
Used to compare differences, find out statistical significance, draw conclusions
Inferential statistics include…
Probability testing
independent variable on a graph
x axis
dependent variable on a graph
y axis
Normal/bell curve
mean, median, and mode are all the same or close
Negative skew
Left skew, most scores are in the high range. test was too easy
Positive skew
Right skew, most scores are in the low range. Test was too hard
Probability variable
p
If p is less than 0.05…
Statistically significant. 95% certainty the result was not due to chance
Null hypothesis
Hypothesis that there is no correlation between populations
Type I error
Occurs when a causal relationship is observed, when none exist (false positive)
Type II error
Occurs when no causal relationships are found, when one does exist (false negative)
