Research methods

Hindsight bias

thinking you knew something all along after outcome

Confirmation bias

Tendency to pay more attention to info that supports our preexisting ideas

Quantitive

Numerical

Hypothesis

relation between two variables, must be falsifiable

Operational definitions

explain how you will measure hypotheses

Representative sampling

goal of selecting sample that represents the larger population

Random sampling

actually random sampling, done by computer

Convenience sampling

collecting data form group that’s easily accessible to you

Stratified sampling

allows researcher to ensure that sample represents pop according to proportion

Confounding variables

any other possible thing that may affect outcome

Random assignment

each participant has equal chance of being placed into either group

Experimenter bias

Unconsciously treating people in each group differently to increase chance of confirming one hypothesis

Double blind study

Participants and researcher can’t affect outcome

Single blind study

participants don’t know which group they’ve been assigned to

Social desirability bias

tendency to try and give answers that reflect well upon oneself

Positive correlation

Presence of one variable predicts presence of other

Negative correlation

Presence of one thing predicts absence of other

Ex post facto study

Seeking to control all other aspects of the research process

Likert scales

Used on surveys for level of agreement/ disagreement

Directionality problem

inability to tell which variable came first

third variable

confounding variable

Naturalistic observation

observing participants in their natural habitat without interacting

central tendency

attempt to mark canter of a distribution, mean, median, mode

Bimodel

2 score appear equally frequently, 2 modes

Frequency polygons

line graphs

Histograms

bar graph

positively skewed

outlier of extreme score, mean higher than median

negatively skewed

outlier that skews it lower, mean lower than median

measures of variability

attempt to depict diversity of distribution (range, standard deviation)

What do standard deviation and variance measure

average distance of any score from the mean, the higher, the more spread out the distribution

Standard deviation is

square root of variance

central tendency

attempt to mark center of a distribution

central tendency examples

mean, median, mode

z scores

measure distance of a score from the mean in units of standard deviation

negative z score means

scores below the mean

normal curve

theoretical bell-shaped curve for which area under curve lying between 2 z scores have been predetermined

what does normal curve allow

allows you to calculate the approx percentage of scores falling between any given z scores, bell shaped

percentiles

distance of the score from 0

z scores

distance of score from mean

percentiles vs z scores

if you score 50th percentile, you are better than 50% of people., but z score of 0

correlations

measure relationship between z variables

positive correlation ex

two variables move in same direction, studying and getting good grades

negative correlation ex

two variables move in opposite directions, cutting classes and bad grades

correlation coefficient

strength of a correlation

-1 correlation coefficient

perfect negative correlation

+1 correlation coefficient

perfect positive coefficient

0 correlation coefficient

weakest possible correlation, none

scatterplot: graphing correlations. Regression line slopes up=

positive correlation

Inferential statistics

determine whether findings can be applied to the larger population from a sample

p value

probability that diff between groups is due to chance

smaller p value =

more significant results

statistically significant p value cutoff

0.05

effect size

quantifying practical significance, large sample is less likely for stastically significant finding

replication crisis

replicating a study using same method to try and get same results

meta analysis

combining results of many studies on same topic to approximate an average

APA

american psychological association