chapter 13 Flashcards
- Which of these does not apply to a ‘statistically significant’ relationship between two categorical variables?
a. The relationship between the two variables is very important from a practical standpoint.
b. The relationship observed in the sample was unlikely to have occurred unless there really is a relationship in the population.
c. The notion that this relationship could have happened by chance is deemed to be implausible.
d. All of the above apply to a ‘statistically significant’ relationship
A
- Which of the following differences in percentages for the two categories of an explanatory variable would be considered to be statistically significant?
a. 50% - 49 % = 1%
b. 50% - 45% = 5%
c. 50% - 40% = 10%
d. Not enough information to tell.
D
- Suppose you find a statistically significant relationship between two categorical variables (with no other supporting evidence available). When can such results correctly lead you conclude a cause and effect relationship?
a. Never.
b. Only when the data were from a randomized experiment.
c. Only when the data were from a random sample.
d. Always; a statistically significant relationship wouldn’t be significant unless there is a cause and effect relationship.
B
- Your mother-in-law says that rubbing a carpet stain with toothpaste before applying stain remover helps take the stain out. You are skeptical. You asked an impartial neighbor to set up a randomized experiment to find out whether there is a relationship between the stain removing method and the outcome. She went home to collect and analyze the data, then called you and said “In a chi-square test, I would choose the alternative hypothesis,” and then hung up. What do you conclude?
a. The toothpaste didn’t make a difference.
b. The toothpaste did help after all.
c. The toothpaste had a significant effect but you don’t know in which way yet.
d. The toothpaste made things worse.
C
- Using the criterion of .05, which of the following results allows a researcher to conclude that a relationship between two categorical variables is statistically significant?
a. p-value = .04
b. p-value = .50
c. p-value = .95
d. None of the above.
A
- Which of the following statements is true about chi-square tests?
a. A large chi-square test statistic results in a large p-value.
b. A large p-value means that there is a good chance that the relationship is statistically significant.
c. If the two variables are not related in the population, then less than 5% of the samples you could ever take would give you a test statistic of 3.84 or larger.
d. All of the above.
C
- Which of the following statements is not true about the chi-square statistic for a 2 x 2 contingency table?
a. If it is greater than 3.84, reject the null hypothesis and accept the alternative hypothesis.
b. If it is greater than 3.84, the relationship in the table is considered to be statistically significant.
c. 95% of the tables for sample data from populations in which there is no relationship will have a chi-square statistic of 3.84 or greater.
d. All of the above are true.
C
- Suppose a chi-square test statistic from a sample of size 1,000 is 38.2 with a p-value of .0001, so the relationship is statistically significant. If the sample size for this study had only been based on a sample size of 100 (but the percentages remained the same), what would the chi-square test statistic have been and what conclusion would have been drawn?
a. Chi-square = 38.2; p-value = .0001; the relationship is statistically significant.
b. Chi-square = 3.82; p-value = .001; the relationship is statistically significant.
c. Chi-square = 3.82; p-value = .052; the relationship is not statistically significant.
d. None of the above.
C
- Suppose researchers say they ‘failed to find a relationship’ between two variables that they thought might have been related. What does this say to you, as an educated consumer of statistical information?
a. You should check to make sure the study was not based on a small number of individuals.
b. The researchers must not have observed any relationship in their sample.
c. There must be no relationship between these two variables in the population.
d. All of the above.
A
- Suppose there is not enough evidence to conclude that the relationship in the population is real. Which of the following is not an equivalent way of saying this?
a. The relationship is not statistically significant.
b. We cannot reject the null hypothesis.
c. We accept the null hypothesis.
d. All of the above.
C
- Suppose that a medical study found a statistically significant relationship between wearing gold jewelry and developing skin cancer. Suppose the study was based on a sample of 100,000 people and had a p-value of .049. How would you react to these results?
a. You feel these results are very convincing since the sample size was so large.
b. You are impressed by the sample size but the p-value is too close to .05 to feel very convinced; the result is marginal.
c. You are skeptical because the high sample size would lead to a small p-value even with a miniscule relationship, and thus gives misleading results.
d. None of the above
C
