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S3- Research II > Tests of Differences and T-Tests; Analysis of Variance > Flashcards

Tests of Differences and T-Tests; Analysis of Variance Flashcards

1
Q

Data Analysis in 3 steps.

  1. ) ________________ (categorical vs. continuous)
  2. ) _______________ (frecuency(percent) for categorical data and mean (SD) or median (IQR) for continuous data)
  3. ) _____________ (statistical hypothesis testing and 95% confidence interval)
A
  1. ) Levels of Measurement
  2. ) Descriptive Statistics
  3. ) Inferential Statistics
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2
Q

What are the 2 common methodologies in inferential statistics?

A
  • Statistical Hypothesis Testing (SHT)

- Confidence Interval (CI)

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3
Q

What are the 2 common uses of inferential statistics and examples?

A
  1. ) Estimate population parameters
    e. x: Determine length of hospital stay for patients with LBP from the sampled medical groups (using CI)
  2. ) Compare between groups
    e. x: Is one treatment more effective than another? (using SHT or CI)
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4
Q

For 𝛼=0.05, p-value <0.05 leads you to _________ the null hypothesis. What does this mean?

A

Reject

-Observed difference shows significant effect.

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5
Q

For 𝛼=0.05, p-value >/=0.05 leads you to ________ the null hypothesis. What does this mean?

A

Retain

-Observed difference is probably due to chance and is not significant.

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6
Q

CI to compare between groups bases on the mean difference:

If the mean difference of SBP between the group with the new medication and the group with the standard treatment was 10 and its 95% CI was between (5.1, 15.7), would we reject or retain the null hypothesis and why?

A

Reject

  • The null hypothesis states that the mean difference = mean SBP (experimental) - mean SBP (control) = 0
  • Since the 95% CI (5.1 to 15.7) does not include 0, we can deduce that with 95% confidence that the two groups are significantly different.
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7
Q

Experimental Research Design:

  • In ________-__________ design subjects are randomly assigned to independent groups.
  • In ________-_________ design subjects act as their own control.
  • By the number of independent variables (=factor), design can be _____-factor or _____-factor.
  • _______-________ design compares changes from pre- to post- test for two or more groups that are formed by random assignment.
  • _________ _________ design and crossover design are the types of within-subject design.
  • _______ design is used when you have both the within-subjects factors and between-subjects factors.
A
  • between-subjects
  • within-subjects
  • single or multi
  • pretest-posttest
  • repeated measures design
  • mixed design
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8
Q

The simplest design in testing the differences?

A
  • Single factor
  • Two levels (2 groups)
  • Between-subjects
  • No repeated measures
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9
Q

__-_____ is a SHT that uses a test statistic with a known probability distribution of the t-distribution. It runs under the assumption that the data is ________, meaning what?

A
  • T-test

- Parametric meaning that the data is normally distributed and has equal variance among groups.

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10
Q

What are the 2 types of t-tests and their differences?

A

Independent t-test (Student’s t-test)
-A SHT that tests whether 2 means collected from two independent samples differ significantly. (between-subject)
Paired t-test
-A SHT that tests whether 2 means collected from the same sample (or paired observations) differ significantly. (within-subject)

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11
Q

For a __________ t-test, the null hypothesis is that the mean value of group 1 is the same as that of group 2. Null is rejected if p-value <0.05.

A

independent t-test

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12
Q

For a ________ t-test, the null hypothesis is that the mean value in pre-session is the same as that in post-session. Null is rejected if p-value <0.05.

A

paired t-test

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13
Q

Example Question 1:

  • A researcher studied a single intervention session of soft tissue mobilization and its effect for increasing external rotation in patients with musculoskeletal shoulder problems. Experimental and control groups were formed through random assignment. Range of motion (ROM) measurements were taken and the improvement was calculated for each subject.
  • Mean improvement (SD) = 16.4 (5.7) degrees for the treatment group.
  • Mean inprovement (SD) = 1.0 (5.2) degrees for the control group.
  • P-value = 0.001
  1. )In the SHT, the null hypothesis was that the mean improvement of the outcome in treatment group was ____ _____ __ the mean improvement in control group.
  2. ) Which SHT would they have applied?
  3. ) Based on the p-value, would they have rejected the null hypothesis?
A
  1. ) the same as
  2. ) independent t-test
  3. ) reject the null
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14
Q

Example Question 2:

  • In an analysis for cultural competency study, data were matched between pre- and post- sessions and the change of the outcome measurement from pre- to post- sessions was tested using a SHT.
  • Mean (SD) = 9.2 (11.7) for the outcome in pre-session
  • Mean (SD) = 17.0 (19.3) for the outcome post-session
  • P-value = 0.025
  1. )In the SHT, the null hypothesis was that the mean improvement of the outcome in treatment group was ____ _____ __ the mean improvement in control group.
  2. ) Which SHT would they have applied?
  3. ) Based on the p-value, would they have rejected the null hypothesis?
A
  1. ) the same as
  2. ) paired t-test
  3. ) reject the null
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15
Q

_________ is a statistical procedure that uses the F-ratio to test whether groups’ means differ.

A

Analysis of Variance (ANOVA)

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16
Q

What are the 5 different ANOVAs? (first 2 are the main ones used)

A
  1. ) ANOVA
  2. ) Repeated Measures ANOVA
  3. ) Factorial ANOVA
  4. ) Mixed ANOVA
  5. ) Analysis of Covariance
17
Q
  • _________ is an overall test of whether multiple groups’ means differ. Thought of as an extension to _________ t-test. Involved with ________-subjects design.
  • ___________ is an ANOVA data that has been measured repeatedly on the same subjects. Thought of as an extension to ________ t-test. Involved with ________-subjects design.
A
  • ANOVA, independent t-test(student), between-subjects

- RM-ANOVA, paired t-test, within-subjects

18
Q 
ANOVA (One-way ANOVA)
For multiple independent groups to compare means.
-Null hypothesis?
-Alternative hypothesis?
-When is null rejected?
A
  • Null hypothesis: The mean values of all groups are the same
  • Alternative hypothesis: For at least a pair of the groups, mean values are not the same.
  • Null hypothesis is rejected if p-value < 0.05
19
Q 
RM-ANOVA (Repeated Measures ANOVA)
For repeatedly measured data to compare means.
-Null hypothesis?
-Alternative hypothesis?
-When is null rejected?
A
  • Null hypothesis: The mean values of all sessions are the same
  • Alternative hypothesis: for at least a pair of the sessions`, mean values are not the same
  • Null hypothesis is rejected if p-value < 0.05
20
Q

Example Question 3:
-A researcher compared the mean scores of self-efficacy for three groups that are high, intermediate, and low clinical experience groups.
-Mean (SD) = 45.0 (11.7) for the outcome in the high experience group.
-Mean (SD) = 44.1 (19.3) for the outcome in the intermediate experience group.
Mean (SD) = 17.0 (27.5) for the outcome in the low experience group.
-P-value = 0.007.

  1. ) In the SHT, the null hypothesis was that the mean outcome values were the same in ____ _____ ______.
  2. ) The alternative hypothesis was that the mean outcome values were not the same in ____ _____ ______.
  3. ) Which SHT would they have applied?
  4. ) Based on the p-value, would they have rejected the null hypothesis?
A
  1. ) all three groups
  2. ) at least two groups
  3. ) ANOVA
  4. ) reject the null
21
Q

Example Question 4:

  • A researcher compared the mean scores of self-efficacy for those low clinical experience group over three different points in time. That are at the end of year 1, year 2, and year 3 of their school.
  • Mean (SD) = 17.0 (27.5) for the outcome at the end of year 1.
  • Mean (SD) = 18.2 (25.0) for the outcome at the end of year 2.
  • Mean (SD) = 19.1 (24.3) for the outcome at the end of year 3,
  • P-value = 0.49
  1. ) In the SHT, the null hypothesis was that the mean outcome values were the same in ____ _____ ______.
  2. ) The alternative hypothesis was that the mean outcome values were not the same in ____ _____ ______.
  3. ) Which SHT would they have applied?
  4. ) Based on the p-value, would they have rejected the null hypothesis?
A
  1. ) all three times
  2. ) at least two times
  3. ) RM-ANOVA
  4. ) fail to reject

S3- Research II (14 decks)

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