Basic terminologies in Research Methodology

Question	Answer
Independent variable	factor believed to bring about change in dependent variable. CAUSE or TREATMENT
Dependent variable	change that results from the intervention (independent variable) OUTCOME
Research/directional hypothesis	predicts expected relationship between variables
Null hypothesis	states that no relationship exists between the variables. relationship found result of chance or sampling error
Null hypothesis accepted	no significant difference observed
Null hypothesis rejected	Signif difference was observed
Nominal data	two or more mutually exclusive categories. male/female, tall/short
Ordinal data	classifies and ranks in terms of the degree they possess a common characteristic. NOT equal intervals. GPA, MMT.
Interval data	Ranks on predetermined EQUAL INTERVALS. NO true ZERO. IQ, F/C temp
Ratio data	ranks based on EQUAL INTERVALS and TRUE ZERO POINT. most precise level of measurement. Goni, weight, force.
Random sampling	all individuals in popn have equal chance of being chosen
Systematic sampliing	selected from a popn by specified intervals
Stratified sampling	Selected from a popn from identified subgroups (height, weight)
Double blind study	subject & investigator not aware of group assignment
Effect size	size of difference between sample means. Allows for a statistical test to find a difference when one really does exist.
Generalizability	the degree to which findings apply to an entire popn
Gold Standard	instrument with established validity that can be used as a standard fro assessing other instruments
Informed consent includes:	info about general nature of study, any risks, what will be done to minimize risks, possible benefits, ethical disclosure.
Control group	group resembling experiemental group that does not receive treatment
Intervening variable	variable that alters the relationship between IND and DEP variables
Validity	degree to which something accurately measures what it is supposed to
Internal validity	degree observed differences in DEP variable are result of IND variable and not some other variable
External Validity	Degree results are generalizable to popn or to environmental settings outside of study
Face Validity	assumption of validity based on appearance of an instrument, psychometrically unsound
Content validity	degree the instrument measures an intended content area - requires item & sampling validity
Concurrent validity	degree scores on one test are related to scores on another criterion test, usu gold standard
Predictive validity	degree test can predict future performance
Construct validity	degree test measures an intended hypothetical abstract concept ( non-observable behaviors or ideas)
Sampling bias	sampling error - sample of convenience, instead of randome selection
Learning effect	pretest influences scores on post test
experimenter bias	expectations of investigator influence results
Hawthorne effect	subject's knowledge of participation in experiment influences results
Placebo effect	subjects respond to a sham with positive effects
Reliability	Degree a test consistently measures what it is intended to
Interrater reliability	consistency of multiple raters
Intrarater reliabilatiy	Individual's consistency in rating
Test-retest reliability	scores on test are stable or consistent over time, measure of instrument stability.
Split half reliability	degree of agreement when test split in half. measure of internal consistency of an instrument
Sensitivity	correctly IDs TRUE POSITIVE
Specificity	correctly IDs TRUE NEGATIVE
Predictive Value	ability to estimate the likelihood that person will test positive or negative for a condition
Independent variable	factor believed to bring about change in dependent variable. CAUSE or TREATMENT
Dependent variable	change that results from the intervention (independent variable) OUTCOME
Research/directional hypothesis	predicts expected relationship between variables
Null hypothesis	states that no relationship exists between the variables. relationship found result of chance or sampling error
Null hypothesis accepted	no significant difference observed
Null hypothesis rejected	Signif difference was observed
Nominal data	two or more mutually exclusive categories. male/female, tall/short
Ordinal data	classifies and ranks in terms of the degree they possess a common characteristic. NOT equal intervals. GPA, MMT.
Interval data	Ranks on predetermined EQUAL INTERVALS. NO true ZERO. IQ, F/C temp
Ratio data	ranks based on EQUAL INTERVALS and TRUE ZERO POINT. most precise level of measurement. Goni, weight, force.
Random sampling	all individuals in popn have equal chance of being chosen
Systematic sampliing	selected from a popn by specified intervals
Stratified sampling	Selected from a popn from identified subgroups (height, weight)
Double blind study	subject & investigator not aware of group assignment
Effect size	size of difference between sample means. Allows for a statistical test to find a difference when one really does exist.
Generalizability	the degree to which findings apply to an entire popn
Gold Standard	instrument with established validity that can be used as a standard fro assessing other instruments
Informed consent includes:	info about general nature of study, any risks, what will be done to minimize risks, possible benefits, ethical disclosure.
Control group	group resembling experiemental group that does not receive treatment
Intervening variable	variable that alters the relationship between IND and DEP variables
Validity	degree to which something accurately measures what it is supposed to
Internal validity	degree observed differences in DEP variable are result of IND variable and not some other variable
External Validity	Degree results are generalizable to popn or to environmental settings outside of study
Face Validity	assumption of validity based on appearance of an instrument, psychometrically unsound
Content validity	degree the instrument measures an intended content area - requires item & sampling validity
Concurrent validity	degree scores on one test are related to scores on another criterion test, usu gold standard
Predictive validity	degree test can predict future performance
Construct validity	degree test measures an intended hypothetical abstract concept ( non-observable behaviors or ideas)
Sampling bias	sampling error - sample of convenience, instead of randome selection
Learning effect	pretest influences scores on post test
experimenter bias	expectations of investigator influence results
Hawthorne effect	subject's knowledge of participation in experiment influences results
Placebo effect	subjects respond to a sham with positive effects
Reliability	Degree a test consistently measures what it is intended to
Interrater reliability	consistency of multiple raters
Intrarater reliabilatiy	Individual's consistency in rating
Test-retest reliability	scores on test are stable or consistent over time, measure of instrument stability.
Split half reliability	degree of agreement when test split in half. measure of internal consistency of an instrument
Sensitivity	correctly IDs TRUE POSITIVE
Specificity	correctly IDs TRUE NEGATIVE
Predictive Value	ability to estimate the likelihood that person will test positive or negative for a condition

Basic statistics for physiotherapists.

Question	Answer
Measures of central tendency	mean, median, mode
Mean	average of all scores
Median	midpoint of all scores
Mode	most frequently occurring score
mean is appropriate for what data types?	interval, ratio
median is appropriate for what data types?	ordinal data
mode is appropriate for what data types?	nominal
Measures of variability	range, standard deviation, normal distribution, percentiles & quartiles
Range	difference between highest and lowest score
Standard Deviation	variability of scores from the mean. most frequently used
How to calculate SD	subtract each score from mean, square each difference, add up all squares, divide by number of scores
Normal distribution	symmetrical bell shaped curve indiecating distribution of scores. Mean/median/mode all similar.
Inferential statistics	allow determination of how likely results can be generalized to a population
Standard error of measurement	an estimate of expected errors in a score, measure of response stability or reliability
Tests of significance	estimation of true differences not due to chance, rejection of null hypothesis
Alpha level	probability level - reselected level of statistical significance. Most commonly .05 or .01 (.05= only 5x out of 100 is the difference due to chance)
Degrees of freedom	based on # of subjects and groups, allows determination of level of significance
Standard error	result of sampling error, expected chance variation among the means
Type 1 error	Null hypothesis rejected when it is true.
Type 2 error	Null hypothesis is not rejected when it is false. means concluded to be due to chance when truly different
How to decrease type 1/2 errors	increase sample size, random selection, valid measures
Parametric statistics	Interval or Ratio data
Assumptions for parametric statistics	normal distribution (usu large representative samples this is met), random sampling performed, variance in groups is equal
T-test	parametric test of significance used to compare 2 independent groups created by random assignment and ID difference at a selected probability level
T-test for independent samples	compares 2 independent groups
T-test for paired samples	compares 2 matched samples (does therapy incr fxn in siblings with autism)
One-tailed T-test	based on directional hypothesis. Evaluates differences in data on only one end of distribution (neg or pos)
Two-tailed T-test	based on a nondirectional hypothesis. Evaluates differences in data on both ends of a distribution. Tests of signif are almost always two-tailed
Inappropriate use of T-test	use to compare more than 2 means within a single sample.
ANOVA	parametric test used to compare 3 or more independent tx groups at a selected probability level.
Simple (one-way) ANOVA	compares multiple groups on a single IND variable. Ex: Balance Master score for 3 different age groups
Factorial ANOVA	compares multiple groups on two or more IND variables. Ex: 3 levels of ankle injury compared for balance and sensory
ANCOVA	Parametric test used to compare 2 or more treatment groups or conditions while also controlling for the effectss of intervening variables.
Nonparametric statistics	ORDINAL or NOMINAL data, testing not based on population parameters
When to use nonparametric	parametric assumptions cannot be met. used with small sample, ordinal or nominal level data. Less powerful than parametric
Chi square test	nonparametric test of significance. Used to compare data in the form of frequency counts in 2 or more mutually exclusive categories (rate treatment preferences)
Correlational statistics	used to determine the relative strength of a relationship between 2 variables
Pearson product-moment coefficient (r)	used to correlate CONTINUOUS data wi
Linear Regression	used to establish relationship between two variables as a basis of prediction
Spearman's Rank	NONPARAMETRIC test to correlate ORDINAL data.