Descriptive statistics, EBP, controls

Question 1

Descriptive statistics

Answer 1

• summarize or describe important characteristics of a population
• typically, data from the population are examined for measures of center, distribution, and variation

Question 2

What are the measures of center?

Answer 2

• Mean
• Median
• Mode

Question 3

Kurtosis

Answer 3

• refers to the “peakedness” of a distribution
• it is a measure of whether the data are peaked of flat relative to a normal distribution
• a high kurtosis distribution has a sharper beak and longer, fatter tails, while a low kurtosis distribution has a more rounded peak and shorter, thinner tails

Question 4

What is a NORMAL distribution?

Answer 4

• a bell-shaped curve with the majority of data clustered around the mean
• approximately 68% of all values within 1 SD away, 95% within 2 SD, and 99% within 3 SD

Question 5

skewness

Answer 5

• refers to the asymmetry in the shape of a distribution
• in a negatively skewed distribution, the mean and median are to the left of the mode and the left tail is elongated

Ex: in a pos skewed distribution, the mean and median are to the right of the mode and the right tail is elongated

Question 6

Coefficient of variation CV

Answer 6

• the CV is the ratio of the standard deviation of a distribution to the mean, expressed as a percentage

Question 7

percentile

Answer 7

• the value below which a certain percent of observations within a distribution will fall
• for examples, the 20th percentile is the value or score below which 20% of scores are found

Question 8

quartiles

Answer 8

• divide the data into four equal parts so that each part represents 1/4 of the sampled population
• the 25th percentile is also known as the first quartile, the 50th percentile as the median or second quartile and the 75th percentile as the third quartile

Question 9

range

Answer 9

-the difference between the maximum and minimum values

Question 10

standard deviation

Answer 10

• descriptive measure of the spread or dispersion of data; the positive square root of the variance
• describing data by means of standard deviation implies that the data are normally distributed

Question 11

variance

Answer 11

• the sum of the squared deviations of each data point from the mean, divided by the number of observations in the sample
• the variance equals the SD squared and therefore is expressed as squared units of the data
• because squared units are difficult to make sense of, the variance is often not reported

Question 12

Epidemiology

Answer 12

• is the study of the causes, distribution, transmission and control of disease in groups of people

Question 13

incidence

Answer 13

• the numbe of new cases of a particular disease or condition in the population at risk during a specified time interval
• often expressed as the number of new cases per 100,000 people at risk

Question 14

prevalence

Answer 14

• the number of existing cases of a disease or condition at a point in time, including new and pre-existing cases

Question 15

steps to practicing Evidence -based PT

Answer 15

1. identify a problem or area of uncertainty about prevention, diagnosis, prognosis or therapy
2. formulate a focused clinical question for a specific pt problem
3. search the literature for relevant clinical articles to answer that question
4. critically appraise each article to determine its validity, impact and applicability
5. integrate the relevant findings in clinical practice along with clinical expertise and pt values
6. assess the outcomes of the selected action

Question 16

P-I-C-O

Answer 16

Patient or problem
intervention
comparison
outcome

Question 17

experimental controls

Answer 17

• an experiment is said to have internal validity when there is confidence that the intervention caused the outcome
• to achieve this result, the researcher will design the experiment to control extraneous variables and sources of bias that could reduce the validity of the results
• there are a number of methods for researchers to help increase the internal validity of an experiment

Question 18

single blind

Answer 18

• the subjects are unaware of the research hypothesis and the group to which they were assigned until the end of the study

Question 19

double blind

Answer 19

• the subjects and certain members of the research team are unaware of the research hypothesis and the group to which each subject was assignes until the end of the study

Question 20

triple blind

Answer 20

the subject, certain members of the research team and data analyzers are unaware of the research hypothesis and the group to which each subject was assigned until the end of the study

Question 21

control group

Answer 21

• a group against which the tx group is compared
• the control should be statistically identical to the tx group, except for4 the variable of interest that is being evaluated in the experiment
• are used to help isolate the effect of the independent variable and eliminate the unintended influence of extraneous factors that can confound the results
• the two most common forms of control are placebo and active

Question 22

matching/pairing

Answer 22

• in research, a strategy for attempting to control for differences between subjects
• investigators identify pairs of subjects who have identical characteristics before randomizing them to ensure that the resultant groups are balanced on important variables that may affect the outcome
• using identical twins is a classic example of matching

Question 23

intention-to-treat analysis

Answer 23

• a method of analysis in which all subjects randomly assigned to one of the tx are analyzed together, regardless of whether they received or completed that tx
• the method preserves the original balance of subject groups achieved through randomization

Question 24

external validity

Answer 24

• the degree to which results of the research study are generalizable to populations or circumstances beyond those included in the study
• threats to external validity include the interaction of tx with the specific type of subjects tested and the place and time in which the experiment is performed

Question 25

internal validity

Answer 25

• the degree to which an intervention being evaluated is the cause of the outcome measured in the study and not the result of extraneous factors
• threats to internal validity include history, maturation, attrition, testing. instrumentation, and regression toward the mean

Question 26

randomization

Answer 26

• a means of assigning subjects to groups in an experiment so that each subject has an equal chance of being assigned to each group
• the most robust method of random assignment is accomplished by computer-generated random numbers or random number tables

Question 27

hawthorne effect

Answer 27

• an untreated subject experiences a change simply from participating in a research study
• the tendency for individuals to change their behavior in response to the fact that they are being observed or studied

Question 28

placebo effect

Answer 28

• a phenomenon in which an inactive tx or procedure that is intended to mimic a real tx causes an improvement in the pt’s condition simply because the pt has the expectation that it will be helpful