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Gravity
Terms in this set (77)
frequency distribution
can be table format or histogram. each value should fit in 1 category. best to use 5-10 classes
variance
a measure of the average deviation or spread of scores around a mean. no negatives. to calculate; obtain mean. subtract mean from each score. add these squared deviations together and divide by sum of numbers
standard deviation
a measure of how much a score varies from the mean. the larger the deviation, the less significant
how to get standard deviation
square root of variance
how much falls between each standard deviation
1 deviation= 68%, 2 deviation=95%, 3rd deviation = 99.7%
how to apply SD
add or subtract the SD from the mean to get each deviation
P-values
represent the likelihood of getting an outcome assuming the null hypothesis is true. results are less likely to occur by chance. measured from 0-1. i being completely due to chance, 0 being no chance. higher values than .05 more likely to occur by chance
Z-scores
measures of standard deviation. measures how much a point deviates from a mean or specific point
Z-score formula
z=(x-u)/o where x is raw score, u is mean, o is standard deviation
what is the total areas that lies between the mean and z=1.0 in a normal distribution
0.3413
student t-test
used to compare two mean scores to determine if there is a statistically significant difference. 2 types
hypothesis
an educated guess, proposition or fundamental rule that is to be tested
null hypothesis
hypothesis that assumes there is no significant statistical difference between tested variables
hypothesis is there is no difference between two drugs. if studies find there is a difference between the effects of two drugs then we...
would reject the null hypothesis
hypothesis that no difference between drugs. and study finds that there is no difference we would...
fail to reject the null hypothesis
type I error for null hypothesis
rejecting a null hypothesis that is true. a used to denote
type II error for null hypothesis
accepting a null hypothesis that is false. b is used to denote
inferential statistics
used to infer information from a sample to the population . chi-square test, correlation, t-test, anova
Chi-square test
used when variables are discrete, sample size small. measures discrepancy between observed and expected results. cannot be negative. <5 are significant values, greater than 5 means not significant
t-test
measures if the means of 2 groups are statistically differnt form each other. used when less than 30 sample size
ANOVA
tests the variance of the means of at least 3 groups
validity
how well the data collection instrument used in the study measures what it is intended to measure.
internal validity
how confidently you can conclude the change in the dependent variable was produced solely by the independent variable and not extraneous ones
external validity
the degree to which the study accurately reflects events that would occur in a real situation
threats to internal validity
history, maturation,m testing, statistical regression, selection, experimental mortality, placebo effect
threats to external validity
failure or inability yo select a random sample, experimenter effect(ppl who know they are being observed may act different), exposure effect, placebo effect
independent variables
what the experimenter changes during the study
dependent variable
what changes when the independent variable changes
characteristics of good research
FINER. feasible, interesting, novel, ethical, relevant
PICO
population, intervention, comparison, outcome
descriptive research
attempt to identify and describe what topic being researched is
analytic research
attempts to establish why it is that way and how it came to be that way
analytical research
may test a hypothesis about the relationship of an exposure to a disease
two main approaches to research are
quantitative and qualitative
historical approach to research
used to determine the meaning of past events through a review of records and literature and use of interviews
descriptive research
variety of studies such as surveys, case studies, document analysis, trend studies. used to describe the presence and distribution of a disease or health condition in a population or sample
retrospective approach/study
looks at a group of ppl, with the disease in the past or present
ecologic study
attempts to relate the outcome with exposure to a suspected risk factor
experimental research
clinical trials. dependent variables studied in a group of people or animals
quasi-experimental approach
lacks inherent control, used when planning further studies
longitudinal epidemiological studies
same group of individuals are studied over an extended time period
prospective study
collection of observations after a decision is made to carry out an investigation
retrospective
collection of observations that have been recorded in the past
case control studies
focus on a group of cases which is then compared with a control group consisting of persons not having the symptom or medical condition
cross-sectional studies
study of subgroups in a specific and limited time frame. sample is assessed at one time
cohort studies
focus on group who show certain attributes or characteristics
bioethics
distinguishes between morally acceptable and unacceptable behavior
nonmaleficence
to do no harm
beneficence
remove existing harm
autonomy
ability to govern ones profession and respect for others
paternalism
doing what provider thinks is right
justice
provide patients what is owed
veracity
being honest
nuremberg code
developed after WWII. unethical research conducted on people in concentration camps.
institutions that conduct medical research are monitored by..
the institutional review board (IRB)
institutional review board
organization in charge of reviewing ethical implications of a research study. it assures the rights and safety of the research subjects. also protects institution against lawsuits
steps in sampling
identify target pop. determine sample size, select sample technique, select sample population
types of sampling
random, stratified random, systemic random, cluster, convenience
random sampling
composed of subjects who are chosen independently of each other. equal opportunity for inclusion
stratified random sampling
used when want to select characteristics of a target pop. subgroups identified. subjects chosen from stratas. not a true random sampling
systematic random sampling
selecting the sample in a predetermined systematic manner. every "nth subject"
cluster sampling
pop. divided into sections. subjects are selected from these clusters
convenience sampling
sample is obtained from a readily available population
qualitative variables
intrinsically non-numerical. categorical,.
quantitative variables
intrinsically numerical, have a scale of measurement or values
nominal
a named category. cannot be arranged in orderly manner, ex. gender
ordinal
ordered categories, can be in order ex age
interval variables
intervals between measurements are meaningful. no inherent zero starting point ex fahrenheit
ratio
inherent zero, represented on scale that begins at absolute zero ex weight
types of visual data representation
bar graphs, histograms, frequency polygons, tables, pie charts, scatter diagrams, bell-shaped curves
bell shaped curve
normal distribution, area under curve =1 or 100%. curve symmetric around curve. extends in both directions
correlation coefficient
a value between 1 and -1. between 0 and 1 is positive. a score of 0 means there is no coorelation. a score of 1 is a perfect positive correlation. as it gets closer to 1 the stronger the correlation
mean
average. add all scores and divide by number of scores. extreme values effect the mean
median
the point the devided the score into 2 equal parts. not affected by extreme values
mode
the value that occurs with the greatest frequency. may have more than one mode
range
difference between the high score and the low score. affected by extreme scores
components of a research article
title, abstract, intro, methods, results, discussion, references
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