Statistics and Research Methods Flashcards
The more heterogenous the distribution of scores,
- The smaller the standard deviation
- The larger the standard deviation
- The more the distribution tends to be skewed
- The greater the chance of excluding extreme scores
- The larger the mean
The larger the standard deviation
For any normal distribution, the 50th percentile corresponds to a z score of
- 0
- 50
- 100
- +/-1
- None of these
0
Other things being equal, an alpha level of .05 should lead to a rejection of the null hypothesis
- More often than when alpha is set at .01
- More often than when alpha is set at .10
- Less often than when alpha is set at .01
- You cannot tell from the information provided
More often than when alpha is set at .01
Rejecting Ho when in fact it should have been accepted, causes
- Standard Error
- Sampling Error
- Omega error
- Type I error
- Type II error
Type I error
When a difference is considered “statistically significant,” the most accurate interpretation of the finding is that the difference is probably
- Meaningful and Profound
- Due to chance and chance alone
- Not due to chance alone
- Not evident in the population
- None of these
Not due to chance alone
The power of a statistical test, such as the independent t-test, can be increased by
- Increasing the sample size
- Increasing the accepted alpha level (making alpha numerically larger)
- Using a one-tailed test
- All of the above
All of the above
The only time the standard deviation may equal zero, is when
- The range is less than 50
- Every score in the distribution is the same
- The range is negative
- None of these, since the standard deviation may never be equal to zero
Every score in the distribution is the same
A scatter plot on which the array of points goes from upper left to lower right indicates
- A positive correlation
- A negative correlation
- A zero correlation
- Any of the above (a, b, or c) depending on the strength of the correlation
- None of the above (a, b, or c)
A negative correlation
When beta is increased (becomes numerically larger)
- Power has decreased
- Power has increased
- The likelihood of rejecting the null hypothesis is maximized
- The likelihood of obtaining a significant difference is maximized
- The possibility of Type I error also is increased
Power has decreased
The T score distribution always assumes a
- Mean of 50, and a SD of 10
- Mean of 100 and a SD of 15
- Mean of 100 and a SD of 10
- Mean of 0 and a SD of 1
- None of the above
Mean of 50, and a SD of 10
The mean of a given normal distribution of raw score is 200 with a standard deviation of 25. What percentage of scores is above 225?
- 5% of the scores
- 10% of the scores
- 16% of the scores
- 25% of the scores
- 34% of the scores
- There is not enough information to tell
16% of the scores
If the standard deviation for a particular distribution is 6, then the variance equals
- 2
- 3
- 6
- 12
- 36
36
The alpha level states the probability of being wrong when
- The null hypothesis is accepted
- The null hypothesis is rejected
- The alternative hypothesis is rejected
- The sample means are assumed to be equal
- The effect size is too small to detect
The null hypothesis is rejected
Of the following correlation coefficients, which expresses the strongest association?
- .76
- .45
- .00
- -.37
- -.95
-.95
Which of the following terms best indicates a process variable (X) through which one variable (A) influences another (B) (e.g., it explains how A influences B)?
- Risk Variable
- Associated Variable
- Mediator Variable
- Moderator Variable
- Correlate
Mediator Variable
Which of the following types of data uses numbers or letters to label categories?
- Nominal
- Ordinal
- Interval
- Rank
- Ratio
Nominal
A correlation coefficient of .80 yields a coefficient of determination of
- 80%
- 40%
- 64%
- 8%
- None of the above
64%
As the sample size increases, degrees of freedom
- Remain the same
- Increase
- Decrease
- Are completely unaffected
Increase
When the alternative hypothesis is accepted
- The “chance” explanation is completely ruled out
- The “chance” explanation, though not ruled out, is judged improbable
- The “chance” explanation is fully accepted
- The “chance” explanation becomes irrelevant
- Beta should be carefully considered as an explanation
The “chance” explanation, though not ruled out, is judged improbable
Which of the following does NOT contribute to a small effect size?
- The heterogeneous sample
- A large standard deviation among the scores on the dependent variable
- Variable experimental procedures
- Use of unreliable measures
- Use of uncontrolled multiple comparisons
Use of uncontrolled multiple comparisons
When the standard deviation of the entire distribution of random sample means has been calculated, the resulting value is called
- The deviation score
- The parameter mean
- The standard error of the mean
- Sampling error
- The mean square value
The standard error of the mean
The smaller the effect size, the greater the likelihood
- a. Of accepting the null hypothesis
- b. Of rejecting the null hypothesis
- c. Of committing a Type I error
- d. Of committing Type II error
- Both a and d
- Both b and c
Both a and d
The mean of a given normal distribution of raw scores is 200 with a standard deviation of 25. Between the raw scores of 150 and 250, there must be
- 50% of scores
- 68% of scores
- 80% of scores
- 84% of scores
- 95% of the scores
- There is not enough information to tell
95% of the scores
A researcher wishes to test the hypothesis that there is a positive association between IQ and musical ability. A random sample of 10 subjects was selected. The subjects were rank-ordered in terms of musical ability. A random sample of 10 subjects was selected. The subjects were rank-ordered in terms of musical ability. Then each subject was given an IQ test. Which of the following statistical tests is most appropriate to determine whether there is a significant relationship between IQ and musical ability in this situation?
- Spearman r
- Pearson r
- Fisher’s z
- Point-biserial correlation
- Phi coefficient
Spearman r
Which of the following statements is NOT true?
- The use of multiple comparisons contributes to an experiment-wise error rate that may be too high
- The experiment-wise error rate is typically higher than the alpha level set for an individual comparison
- The experiment-wise error rate is typically lower than the alpha level set for an individual comparison.
- An elevated experiment-wise error rate contributes to Type I error
- Problems with the experiment-wise error rate may cause the researcher to erroneously reject the null hypothesis
The experiment-wise error rate is typically lower than the alpha level set for an individual comparison.
When a distribution shows a large majority of high scores and a few very low scores, the distribution is said to be
- Skewed to the right
- Skewed to the left
- Skewed to the middle
- Bimodal
- None of the above
Skewed to the left