MCAT Physchology

dependent variable - *The outcome factor; the variable that may change in response to manipulations of the independent variable and is measured.

independent variable - *The experimental factor that is manipulated; the variable whose effect is being studied.

risks to participants should only be taken if... - *necessary and are outweighed by the expected benefits

When is deception okay? - *when knowledge ahead of time would influence participants' responses. You must debrief the participant afterwards.

What is a vulnerable population? - *is one that is not able to protect its members; self-interests in the course of being test subjects

Examples of people considered to be apart of vulnerable populations (3) - *- lack the cognitive capability to understand risks
- lack the linguistic abilities to understand consent
- monetary incentives would disproportionately convince them to partake in risky work

what are the 2 types of variables? - *categorical and numerical

categorical variable - *variables that are categories

What are 2 examples of categorical variable? - *nominal and ordinal

Categorical variable: nominal variables - *used to name, label or categorize particular attributes that are being measured, includes an individual's name or gender

Categorical variable: ordinal variable - *a qualitative variable that incorporates an ordered position, or ranking such as letter grades

quantitative variable - *variables that are numbers and behave like numbers such as height, salary and weight

What are the 2 types of quantitative variables? - *interval and ratio

Quantitative variable: interval variable - *measures the intervals between values on a scales as it has an arbitrary zero point such as temperature or credit score

Quantitative variable: ratio variable - *has a meaningful zero and equal distance between two points such as Kelvin or height

Experimental study - *the researcher manipulates one of the variables and tries to determine how the manipulation influences other variables

WHat types of controls are used in experimental studies? (2) - *negative and positive controls

negative controls in an experimental study - *are procedures not expected to produce results (ex. a placebo)

positive controls in an experimental study - *are procedures with well-understood, and usually positive effects (ex. a previously established vaccine)

What are the 3 steps of an experimental study design? - *recruit, sort and repeat

simple random sampling - *every member of the population has an equal probability of being selected for the sample (purely random)

cluster random sampling - *dividing the total population into groups (or clusters), then using simple random sampling to select which clusters participate; all observations in a selected cluster are included in the sample

stratified random sampling - *Population divided into subgroups (strata) or subpopulations and random samples taken from each strata - we expect there to be a difference

Snowballing sampling - *Participants recommend other participants for the study - researchers do this when it is hard to find specific people with a particular trait being studied

bias - *A particular preference or point of view that is personal, rather than scientific.

Random sorting - *when individuals are sorted randomly into the trial and control groups

block design sorting - *group by a particular trait and then randomised to make sure there are equal numbers of each group into the corresponding placebo/vaccine groups

matched pair design - *a design in which one creates a set of two participants who are highly similar on a key trait and then randomly assigns individuals in the pair to different groups

Blinding - *any individual associated with an experiment who is not aware of how subjects have been allocated to treatment groups

unblinded study - *everyone knows which participants are in which group

Single-blinded study - *the participant doesn't know which group they are in but the researcher does

double-blinded study - *neither the subjects nor the investigators know who is receiving the active treatment

observational studies - *Researchers carefully and systematically observe and record behavior without interfering with behavior.

correlation study - *a descriptive study that looks for a consistent relationship between two phenomena

cross-sectional study - *study a sample at one point in time

longitudinal study - *a study that observes the same participants on many occasions over a long period of time

quasi-experimental study - *a study that uses intact groups rather than random assignment of subjects to groups and applies an intervention

case-control study - *Observational study where 2 people differing in outcome are identified and compared to find a causal factor

case study - *an observation technique in which one person is studied in depth in the hope of revealing universal principles or what variables are important

mixed-methods study - *research study that includes elements of both quantitative and qualitative research to paint a more complete picture of any of the individual methods

descriptive statistics - *describes the data not seeking to find relationships within it

Descriptive statistics are used for both measures of \____ and measures of \____ - *central tendency - which estimates the center position of values in a data set

dispersion - which describes how spread out the values of the data are

Discrete Data (Quantitative) - *numerical data restricted to certain values (integers)

Continuous Data - *are not restricted to certain number values

What are 3 common measures of central tendency? - *mean, median, mode

mean - *the average value of a group of numbers

median - *the middle score in a distribution; half the scores are above it and half are below it

mode - *the value that most frequently occurs

outlier - *A value much greater or much less than the others in a data set which skews the mean

left-skewed distribution - *An asymmetric frequency distribution in which there are some unusually low scores that distort the mean to be less than the median.

right skewed distribution - *An asymmetric frequency distribution in which there are some unusually high scores that distort the mean to be greater than the median.

measures of dispersion (variability) - *range, interquartile range, variance/standard deviation

range - *calculated by subtracting the smallest value in a set from the largest value

Percentile - *A point on a ranking scale of 0 to 100. The 50th percentile is the midpoint; half the people in the population being studied rank higher and half rank lower.

What are quartiles? - *Quartiles are one of four equal portions of an ordered data set.

To fine the 1st Quartile, take 0.25n. If this is not an integer, take the number on either side and average them.

The 2nd Quartile is the median.

To find the 3rd Quartile, take 0.75n. If this is not an integer, take the number on either side and average them.

Interquartile Range (IQR) - *measures the spread of the center half of the data and is determined by finding the difference between the third and first quartiles

IQR \= Q3 - Q1

Standard Deviation (SD) - *A measure of variability that indicates the average difference between the scores and their mean.

What does it mean if the data is more spread up? - *the larger the standard deviation

Variance - *the square of the standard deviation

How to read a box plot - *Box shows from Q1 - Q3. The "whiskers" are 1.5 iqr below Q1 and above Q3. All above / below those are outliers.
The middle line is the median value

error - *is the difference between the true value and a given measurement

random error - *occurs in all types of measurements and is created by lack of instrument sensitivity as well as human errors

random error decreases \___ - *precision

systematic error - *shifts all measurements in one direction leading to bias

systematic error decreases \___ - *accuracy

observer bias - *an observer intentionally or unintentionally records a measurement incorrectly

Instrument bias - *results from consistent malfunctioning of an instrument

subject bias - *results from situations in which study subjects intentionally or unintentionally misrepresent information

p-value - *represents the probability of the observations occurring due to chance alone

Null Hypothesis (H0) - *the statistical hypothesis tested by the statistical procedure; usually a hypothesis of no difference or no relationship

p-value < 0.05 - *reject the null hypothesis, statistically significant

standard error - *is the standard deviation of a sampling distribution

confidence interval - *an estimated range of values that is likely to include an unknown population parameter at a given confidence level

level of confidence - *the probability that the interval estimate contains the population parameter

95% confidence interval - *the range within which the true population mean lies, with 95% certainty

alpha -level - *the probability level used by researchers to indicate the cutoff probability level (highest value) that allows them to reject the null hypothesis

if p < a - *then reject the H0 and accept the relationship

if p \> a - *fail to reject H0 and there is no relationship

Type I error - *false positive - occurs if the null hypothesis is rejected when it is true

Type II error - *false negative - occurs if the null hypothesis is not rejected when it is false

correlation - *estimates how much 2 variables are associated via a correlation coefficient (r)

a correlation coefficient of 1 indicates ... - *a perfect linear relationship with a positive slope

a correlation coefficient of -1 indicates ... - *a perfect linear relationship with a negative slope

a correlation coefficient of 0 indicates ... - *there is no linear association between two variables

simple linear regression - *describes how one variable is associated with another and is an extension of correlation

residual - *the difference between an observed value of the response variable and the predicted value

chi-square test - *is used when all variables are categorical

t-test - *used to compare the average values of a quantitative variable between two categorical groups

Analysis of Variance (ANOVA) - *analysis of variance test used for designs with three or more sample means

internal validity - *the degree to which the independent variable has been demonstrated to cause the dependent variable. Confounding variables are big threats to internal validity

Temporality (Hill's Criteria) - *the exposure must occur before the outcome (cause before effect)

External validity (generalizability) - *refers to the ability of a research design to provide results that can be generalised to other situations

What 2 factors does high external validity depend on? - *1. participants in the study - should be a representative sample
2. physical realism of the research setting - similar and relevant characteristics of the natural situation

ethnographic methods - *observing social interactions in real social settings (cultural settings)

What 2 approaches can medicine take? - *biomedical approach and the biopsychosocial approach