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S3- Research II > Inferential Statistics and Experimental Research > Flashcards

Inferential Statistics and Experimental Research Flashcards

1
Q

INFERENTIAL STATISTICS

A

INFERENTIAL STATISTICS

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2
Q

Descriptive statistics are used to describe ______ while Inferential statistics are used to make decision about the __________ group based on the information of the ________ group.

A
  • data

- population, sample

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3
Q

In descriptive statistics you use mean (SD) for _________ data and count (percent) for __________ data.

A
  • continuous

- categorical

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4
Q

What is the difference between population and sample?

A

Population

  • contains all subjects of interest
  • impractical
  • numerical property = parameter (pop mean, proportion)

Sample

  • part of selection that s required to be random
  • best approach available
  • quantity from it = statistic (sample mean, proportion)
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5
Q

Sample selection is required to be ______ but might not be good because random selection doesn’t gaurantee proportional representation of all parts of the population.

A

random

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6
Q
  • The standard deviation of sample means is called what?

- What is the formula for this?

A
  • SEM (standard error of the mean)

- s/sqrt (n) where s=the sample SD and n=sample size

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7
Q

What does the Central Limit Theorem state?

A

Sampling distribution of the sample means approaches a normal distribution as the sample size gets larger.

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8
Q

The SEM for a smaller sample size is typically _______ than that of a larger sample size. What does this mean?

A

larger, means there is more variability

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9
Q

What are the 2 common methodologies for inferential statistics?

A
  • Statistical Hypothesis Testing (SHT)

- Confidence Interval (CI)

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10
Q

What are some common uses of inferential statistics?

A
  • estimate population parameters

- compare effects between groups

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11
Q

What are the 4 steps of the procedure for SHT?

A
  1. ) State the statistical hypothesis (null and alternative hypothesis)
  2. ) Select a level of significance (α)
  3. ) Decide which test to use (t-test, analysis of variance, Mann-Whitney U Test, chi-square test, McNemar test)
  4. ) Make a decision to reject or retain the null hypothesis based on resulting quantity called p-value
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12
Q

What is the difference between null and alternative hypothesis?

A

Null Hypothesis
-group means are not different
Alternative Hypothesis
-there is a true difference between groups, and the treatment was effective

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13
Q

What is a p-value?

A

Major resulting value of running a statistical hypothesis test and quantifies how consistent your sample values are with the null hypothesis.

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14
Q

The p value ranges from 0-1. What does a large p-value mean? What does a small p-value mean?

A
  • Large p-value- your sample values are consistent with the null hypothesis
  • Small p-value- your sample values are not consistent with the null hypothesis
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15
Q

For a p-value (α) level <0.05 you _______ the null hypothesis. What does this mean?

A
  • Reject

- This means that the observed difference shows significant effect

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16
Q

For a p-value (α) level >0.05 you _______ the null hypothesis. What does this mean?

A
  • Retain

- This means the observed difference is probably due to chance and is not significant

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17
Q

Difference between a Type I and Type II error?

A

Type I = rejection of a true null hypothesis

Type II = non-rejection of a false null hypothesis

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18
Q

What is a confidence interval?

A

A range of values so defined that there is a specified probability that the value of a parameter lies within it.

19
Q

Confidence Interval Example:
Fitzgerald et al estimated the population mean for lumbar spinal extension for 30-39 year old individuals. Based on the random sample of 42 individuals, they determined that mean=40.0 degrees and sd=8.8 degrees. How can you tell how accurate this estimate is?

  • Find the SEM.
  • Assess the 95% confidence interval.
A

SEM
=sd/sqrt (n) = 8.8/sqrt(42) = 1.36

CI
=(40-21.36),(40+21.36)
=37.3 - 42.7

20
Q
  • A narrower CI implies higher ________ with less ___________.
  • A wider CI implies lower __________ with increased ___________.
A
  • precision, variability

- precision, coverage (variability)

21
Q

CI can be used to estimate population parameters, but it can also be used to compare effects between ________.

A

groups

22
Q

CI can be used to compare between groups based on the __________ or the ______.

A
  • mean difference

- ratio

23
Q

The effect is not significant if the CI contains the ___________. The effect is significant if the CI doesn’t contain the _________.

A
  • null value

- null value

24
Q
  • Null Value for the Mean Difference = _____

- Null Value for the Ratio = ______

A
  • 0

- 1

25
Q

The mean difference of SBP was 10 and its 95% CI was (5.2, 15.7). Is the difference significant?

A

Yes, CI does not contain null value.

26
Q

The odds ratio of having not been physically active for patients with breast cancer over the controls was 2 and its 95% CI was (0.5, 4.5). Is the difference significant?

A

No, Ci contains the null value.

27
Q

Summary for Inferential Statistics:

  • The purpose of using inferential statistics is to make decision about the _________ group based on the information of the _______ group
  • Sampling errors are the differences between the ________ values and the _______ values
  • Sample mean together with its standard error can picture what the sampling distribution looks like and can provide an interval _______ for the population mean
  • ________________ is performed to make a decision about the population by rejecting or retaining the null hypothesis based on the resulting quantity called p-value
  • ______ as a result of running a statistical hypothesis testing is used to make decision
  • In a statistical hypothesis testing are the potential errors including type _ and type __ errors
  • Confidence interval for the mean difference is checked for inclusion of its null value of __ for the significant effect
  • Confidence interval for the ratio is checked for including of its null value of __ for the significant effect
A
  • population, sample
  • sample, population
  • estimate
  • SHT (statistical hypothesis testing)
  • p-value
  • Type I (reject true null), Type II (non-rej of false null)
  • 0
  • 1
28
Q

EXPERIMENTAL RESEARCH

A

EXPERIMENTAL RESEARCH

29
Q

What is the purpose of experimental research?

A

Provide a structure for evaluating the cause-and-effect relationship between a set of independent and dependent variables.

30
Q

The term ________ _____ is often used to describe experimental studies that examine the effect of intervention on human subjects.

A

Clinical Trial

31
Q

What are the 4 phases of Clinical Trials?

A

Phase I
-Show safety on small sample of subjects, help to understand mechanism of action.
Phase II
-Once shown to be safe, this phase demonstrates effectiveness on relatively small samples.
Phase III
-Randomized, usually blind, experiment comparing against a placebo. Large scale studies with 100s or 1000s of subjects.
Phase IV
-Once approved by FDA, this phase involves continual investigation on its effects.

32
Q

What is considered the gold standard of true experimental designs?

A

RCT

33
Q

What is the difference between a True-Experimental Design and a Quasi-Experimental Design?

A

True-Experimental Design

  • subjects are randomly assigned
  • at least 2 comparison groups

Quasi-Experimental Design

  • does not meet the requirements of a true experiment
  • lacking random assignment or comparison groups, or both
  • used when a true-experimental design is not feasible
  • accommodates for the limitations of natural settings
34
Q

What is the difference between Between-Subjects Design and Within-Subject Design?

A

Between-Subjects Design

  • subjects randomly assigned to independent groups
  • completely randomized designs

Within-Subjects Design

  • subjects act as their own control
  • repeated measures design
35
Q

Difference between Single-Factor Design and Multi-Factor Design?

A

Single-Factor Design (one-way design)

  • structures the investigation of one independent variable
  • easy to develop
  • can’t account for simultaneous interactions of several variables

Multi-Factor Design (multi-way design)

  • incorporates two or more independent variables
  • can name variously
36
Q

Pretest-Posttest Control Group Design is the basic structure of a _________ and compares two or more groups that are formed by _______ assignment.

A
  • RCT

- random

37
Q

What is considered the scientific standard in clinical research for establishing a cause-and-effect relationship?

A

Pretest-Posttest Control Group Design

38
Q

When is a Posttest Only Control Group Design used?

A

When a pretest is impractical or potentially reactive.

39
Q

_____________ design involves the ability to control the potential influence of individual differences and uses subjects as their own control.

A

Repeated Measures Design

40
Q

Repeated Measures Design has a potential for _________ effects and ________ effects. This design is only used when the outcome measure will revert back to baseline between interventions.

A
  • practice

- carryover

41
Q

What is a Crossovere Design?

A

Half the subjects receive treatment A followed by B; half receive treatment B followed by A.

42
Q

Crossover Design is only used when patient’s condition will not change over time and is not a reasonable approach when treatment effects are _____. _______ period is essential.

A
  • slow

- Washout

43
Q

Mixed Design has both the _______-subjects and _________-subjects factors.

A

within-subjects and between-subjects

44
Q

Summary For Experimental Research:

  • Experimental research provides a structure for evaluating the ______________ relationship between a set of independent and dependent variables
  • In true experimental design subjects are ________ assigned to at least two comparison groups
  • When a true-experimental design is not feasible, ____-experimental design is useful lacking random assignment or comparison groups, or both
  • In between-subjects design subjects are _______ assigned to independent groups
  • In within-subjects design subjects act as their own ________
  • By the number of independent variables (=factors), design can be _______-factor or ______-factor
  • _______-_______ design compares the changes from pre- to post- test for two or more groups that are formed by random assignment
  • When a pretest is either impractical or potentially reactive, _________ only design is useful
  • Repeated measures design and crossover design are the types of _______-subject design
  • Mixed design is available when you have _____ the within-subjects factors and between-subjects factors
A
  • cause-and-effect
  • randomly
  • quasi
  • randomly
  • control
  • single-factor or multi-factor
  • pretest-posttest
  • posttest
  • within
  • both

S3- Research II (14 decks)

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