Understanding P-Value Interpretation
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Questions and Answers

Which term is used to describe a numerical characteristic of a population?

  • Parameter (correct)
  • Statistic
  • Estimate
  • Random variable

What does the sample mean 'x-bar' represent?

  • Sample estimate
  • Population mean
  • Population parameter
  • Sample statistic (correct)

What is the relationship between parameters and statistics?

  • Parameters are only applicable to samples
  • There is no relationship between them
  • They are interchangeable terms
  • Statistics are estimates of parameters (correct)

How do 'observed' values help towards a knowledge of the 'true' values?

<p>By allowing us to test hypotheses about the observed values (A)</p> Signup and view all the answers

What type of value does sample mean 'x-bar' estimate?

<p>Population parameter (C)</p> Signup and view all the answers

What is the odds ratio used for in epidemiological studies?

<p>Comparing patients with a certain condition to patients without that condition (C)</p> Signup and view all the answers

In a 2x2 contingency table for a case-control study, what does 'a' represent?

<p>Cases with the risk factor and the primary outcome (A)</p> Signup and view all the answers

What does the odds ratio estimate in a case-control study?

<p>Population relative risk (D)</p> Signup and view all the answers

What do epidemiologists hope to achieve when estimating population characteristics like incidence and prevalence?

<p>To obtain precise measurements of the true values (D)</p> Signup and view all the answers

What does hypothesis testing allow statisticians to do?

<p>Formally accept or reject statistical hypotheses (A)</p> Signup and view all the answers

What is the purpose of interpretation in hypothesis testing?

<p>To assess the strength of evidence against a hypothesis (D)</p> Signup and view all the answers

What is the probability known as in hypothesis testing?

<p>p-value (C)</p> Signup and view all the answers

In epidemiological studies, what does random variation refer to?

<p>The distortion of results by chance in observed data (D)</p> Signup and view all the answers

What kind of statement can be made informally about observed data?

<p>&quot;The true values are probably fairly close to what we observed&quot; (A)</p> Signup and view all the answers

What is the argument structure used in interpretation of observed incidence rate ratios (IRR)?

<p>'True' IRR vs. observed IRR vs. probability of observing IRR by chance (C)</p> Signup and view all the answers

What does hypothesis testing allow statisticians to do?

<p>Formally accept or reject statistical hypotheses (B)</p> Signup and view all the answers

What is the purpose of interpretation in hypothesis testing?

<p>To assess the strength of evidence against a hypothesis (C)</p> Signup and view all the answers

What is the difference between systematic and random variation?

<p>Systematic variation is a consistent difference between the recorded value and the true value, while random variation is due to chance differences in true and recorded values. (A)</p> Signup and view all the answers

Which of the following best describes random variation?

<p>Random variation involves chance differences in the true and recorded values. (C)</p> Signup and view all the answers

Why might the incidence of TB fluctuate up and down on different occasions?

<p>Because of the influence of random variation. (D)</p> Signup and view all the answers

What is the 'true' risk referred to in the context of epidemiological observations?

<p>The underlying risk or incidence that may be affected by random variation. (B)</p> Signup and view all the answers

How is the proportion of people with diabetes in a random sample of 200 in Ranya related to the 'true' prevalence of diabetes in Ranya?

<p>It is influenced by random fluctuations in diabetes prevalence. (B)</p> Signup and view all the answers

What does an odds represent in the context of epidemiological measurements?

<p>The chances of something happening relative to the chances of all things happening. (B)</p> Signup and view all the answers

How can the difference in survival between 200 cases of breast cancer treated with Tamoxifen and 200 untreated cases be defined?

<p>It is affected by random fluctuations in survival outcomes. (C)</p> Signup and view all the answers

What do risk factors refer to in epidemiology?

<p>Risk factors are linked to personal habits or environmental exposures associated with increased disease probability. (D)</p> Signup and view all the answers

How are odds different from risks in epidemiological measurements?

<p>Risks indicate probabilities of disease occurrence, while odds indicate probabilities relative to all possible events. (D)</p> Signup and view all the answers

What is the primary purpose of distinguishing between the 'true' or 'underlying' value and observed measurements in epidemiological studies?

<p>To differentiate between fluctuations influenced by random variation and genuine changes in disease risk. (D)</p> Signup and view all the answers

Why do we need to know about the 'true' risk in epidemiological studies?

<p>To understand if there are genuine changes in disease risk as opposed to fluctuations influenced by random variation. (C)</p> Signup and view all the answers

What does an association refer to in epidemiology?

<p>A statistical relationship between two or more variables. (D)</p> Signup and view all the answers

What is the purpose of a 2x2 table in epidemiology?

<p>To assess the strength of association between exposure and outcome (D)</p> Signup and view all the answers

In the context of the text, what does 'E+' represent in the 2x2 table?

<p>Subjects who were exposed to the risk factor (C)</p> Signup and view all the answers

What does 'c+d' represent in the 2x2 table for this situation?

<p>Total number of subjects who do not have the exposure (D)</p> Signup and view all the answers

What is the purpose of calculating relative risk in epidemiology?

<p>To assess the likelihood that an association represents a causal relationship (A)</p> Signup and view all the answers

What does a relative risk (RR) value greater than 1 indicate?

<p>A positive association between exposure and outcome (B)</p> Signup and view all the answers

In the context of epidemiology, what does 'RR = Incidence of outcome among those having the Exposure / Incidence of outcome among those not having the Exposure' represent?

<p>Relative risk (RR) (A)</p> Signup and view all the answers

What is indicated if the relative risk (RR) is equal to 1?

<p>No association between exposure and outcome (A)</p> Signup and view all the answers

What does a relative risk (RR) value less than 1 indicate?

<p>A negative association between exposure and outcome (B)</p> Signup and view all the answers

In epidemiology, what does a relative risk (RR) value of 0.5 suggest about the relationship between exposure and outcome?

<p>Smoking reduces the risk of getting IHD by half (A)</p> Signup and view all the answers

What is the best indicator of the strength of an association between exposure and outcome in epidemiology?

<p>Relative risk (or odds ratio) (A)</p> Signup and view all the answers

If we observe 80 cases of breast cancer in 1,500 elderly women, what is the 95% confidence interval for the ‘true’ prevalence?

<p>0.042 to 0.066 per 1,000 elderly women (D)</p> Signup and view all the answers

What is the error factor for an incidence rate ratio (IRR) considering the number of events in both populations?

<p>3.13 (C)</p> Signup and view all the answers

What is used to calculate the Standardized Mortality Ratio (SMR)?

<p>O/E (B)</p> Signup and view all the answers

Why is estimation considered a better approach than hypothesis testing?

<p>Because it provides a range of 'true' values consistent with the observed data (A)</p> Signup and view all the answers

If the null hypothesis value lies within the 95% confidence interval, what can be concluded?

<p>The null hypothesis value is consistent with the observed data (C)</p> Signup and view all the answers

In the example of the IRR for strokes, what does it mean if 1.0 lies within the 95% confidence interval?

<p>'True' IRR of 1.0 is consistent with the observed data (D)</p> Signup and view all the answers

What is calculated using O (the number of deaths observed in the local population) in SMR?

<p>(O/E) (D)</p> Signup and view all the answers

What does the 95% confidence interval represent?

<p>'True' values consistent with the observed data (D)</p> Signup and view all the answers

What does a p-value greater than 0.05 generally indicate?

<p>Little or no evidence against the hypothesis (C)</p> Signup and view all the answers

If the incidence of leukemia in Town C is statistically significantly higher than in Town D (p < 0.001), what does this indicate?

<p>Some factor other than chance is likely responsible for the observed difference (C)</p> Signup and view all the answers

What does it mean if a p-value is less than 0.05 in a hypothesis test?

<p>It is statistically significant evidence against the null hypothesis (A)</p> Signup and view all the answers

If the data do not provide sufficient evidence that a new treatment is beneficial, what could be the reason for this?

<p>Both a and b (D)</p> Signup and view all the answers

What does a rejected null hypothesis (p=0.01) indicate?

<p>The observed data is deemed to have provided sufficient evidence against the null hypothesis (C)</p> Signup and view all the answers

What is the purpose of defining a range within which the excess risk or possible benefit are likely to lie?

<p>To provide more useful information than null hypothesis tests (C)</p> Signup and view all the answers

What can be concluded if a series of hypothesis tests about the 'true' excess risk of TB in Basra indicate that hypothesized values between 1.1 and 1.5 are 'consistent with' the data?

<p>'True' excess risk of TB in Basra probably lies between 1.1 and 1.5 (A)</p> Signup and view all the answers

What can we say about Basra residents based on an observed incidence rate ratio (IRR) of 1.3 for tuberculosis compared with other Iraq residents?

<p>'True' IRR probably lies between 1.2 and 1.6 (A)</p> Signup and view all the answers

How does statistical theory allow us to interpret the 'true' value of any measure used in this module?

<p>[Observed value ÷ e.f.] and [Observed value × e.f.] provide an estimated range within which the 'true' value lies (B)</p> Signup and view all the answers

What does it mean when a hypothesis test reflects a lack of information due to few data available?

<p>'True' value cannot be determined with few data available (A)</p> Signup and view all the answers

What can be concluded about neutron therapy based on Example 5 where 240 deaths out of 600 patients (40%) were on neutron therapy and 255 deaths out of 600 patients (44%) were on radiotherapy, resulting in a p-value of 0.4?

<p>There is insufficient evidence to reject the null hypothesis about neutron therapy's effectiveness (A)</p> Signup and view all the answers

What does an observed p-value of 0.0001 for IRR = 0.8 indicate in a power station example?

<p>The null hypothesis is rejected with strong evidence against it (C)</p> Signup and view all the answers

In what scenario might there be little or no evidence from considered data against a hypothesis?

<p>When there are too few data available for analysis (D)</p> Signup and view all the answers

What is the primary purpose of distinguishing between 'observed' and 'true' epidemiological quantities?

<p>To test hypotheses about the 'true' values and calculate confidence intervals (A)</p> Signup and view all the answers

What is the relationship between parameters and statistics in epidemiology?

<p>Parameters are characteristics of a population, while statistics are values calculated in a sample (D)</p> Signup and view all the answers

What does an observed p-value of 0.0001 for IRR = 0.8 indicate in a power station example?

<p>The IRR is significantly different from the 'true' value (B)</p> Signup and view all the answers

What does a relative risk (RR) value greater than 1 indicate in epidemiology?

<p>An increased risk associated with exposure (A)</p> Signup and view all the answers

Why is estimation considered a better approach than hypothesis testing in epidemiology?

<p>Estimation allows for a range of possible values, rather than a simple accept/reject decision (C)</p> Signup and view all the answers

What can be concluded if the null hypothesis value lies within the 95% confidence interval?

<p>The null hypothesis is accepted (A)</p> Signup and view all the answers

What is systematic variation in epidemiology?

<p>A consistent difference between the recorded value and the true value in a series of observations (D)</p> Signup and view all the answers

What is random variation in epidemiology?

<p>Fluctuations in disease incidence due to age and luck (A)</p> Signup and view all the answers

What does the term 'true risk' refer to in epidemiology?

<p>The underlying risk or incidence of a disease or health condition (A)</p> Signup and view all the answers

What is the purpose of distinguishing between the 'true' or 'underlying' value and observed measurements in epidemiological studies?

<p>To understand if there are changes in the underlying risk factors (A)</p> Signup and view all the answers

What is the difference between risk and odds in epidemiological measurements?

<p>Risk represents the chances of something happening, while odds represent the chances of it not happening (D)</p> Signup and view all the answers

Why do we need to know about the 'true' risk in epidemiological studies?

<p>To understand if there are changes in the underlying risk factors (A)</p> Signup and view all the answers

What is an association in epidemiology?

<p>A statistical relationship between two or more variables (B)</p> Signup and view all the answers

In epidemiological studies, what do risk factors refer to?

<p>Aspects of personal habits or environmental exposures associated with increased probability of occurrence of a disease (B)</p> Signup and view all the answers

What is the odds ratio used for in epidemiological studies?

<p>Comparing patients who already have a certain condition with patients who do not (B)</p> Signup and view all the answers

What does a relative risk (RR) value greater than 1 indicate?

<p>The exposure increases the risk of the outcome (C)</p> Signup and view all the answers

What is the purpose of hypothesis testing in statistics?

<p>To accept or reject statistical hypotheses (D)</p> Signup and view all the answers

What is indicated if the relative risk (RR) is equal to 1?

<p>There is no association between the exposure and outcome (B)</p> Signup and view all the answers

What does an observed p-value of 0.0001 for IRR = 0.8 indicate in a power station example?

<p>Strong evidence against the null hypothesis (A)</p> Signup and view all the answers

What can be concluded about neutron therapy based on Example 5?

<p>Neutron therapy has no significant effect on survival (C)</p> Signup and view all the answers

What does it mean if a p-value is less than 0.05 in a hypothesis test?

<p>There is strong evidence against the null hypothesis (B)</p> Signup and view all the answers

What does a rejected null hypothesis (p=0.01) indicate?

<p>'True' IRR for leukemia is raised at all (D)</p> Signup and view all the answers

What do epidemiologists hope to achieve when estimating population characteristics like incidence and prevalence?

<p>To find out the true value of these measures (C)</p> Signup and view all the answers

How do 'observed' values help towards a knowledge of the 'true' values?

<p>'True' values may be inferred from observed values (C)</p> Signup and view all the answers

What do risk factors refer to in epidemiology?

<p>Exposures or characteristics associated with an increased risk of disease or health outcome (A)</p> Signup and view all the answers

What does a relative risk (RR) value less than 1 indicate?

<p>The exposure decreases the risk of the outcome (D)</p> Signup and view all the answers

What is the purpose of using a 2x2 table in epidemiology?

<p>To determine the strength of the association between exposure and outcome (C)</p> Signup and view all the answers

What does the relative risk (RR) value of 0.5 suggest about the relationship between exposure and outcome in epidemiology?

<p>Exposure reduces the risk of the outcome by half (C)</p> Signup and view all the answers

If the data do not provide sufficient evidence that a new treatment is beneficial, what could be the reason for this?

<p>The sample size was too small to detect a significant effect (C)</p> Signup and view all the answers

What does an observed p-value of 0.0001 for IRR = 0.8 indicate in a power station example?

<p>The null hypothesis should be rejected (C)</p> Signup and view all the answers

What is indicated if the relative risk (RR) is equal to 1?

<p>There is no association between exposure and outcome (C)</p> Signup and view all the answers

What is calculated using 'O' (the number of deaths observed in the local population) in SMR?

<p>The Standardized Mortality Ratio (SMR) (D)</p> Signup and view all the answers

What do epidemiologists hope to achieve when estimating population characteristics like incidence and prevalence?

<p>To understand the distribution and determinants of health-related states or events (B)</p> Signup and view all the answers

What does it mean when a hypothesis test reflects a lack of information due to few data available?

<p>'True' values are not accurately represented in observed measurements (C)</p> Signup and view all the answers

'RR = Incidence of outcome among those having the Exposure / Incidence of outcome among those not having the Exposure' represents what in epidemiology?

<p>'Best indicator of the strength of an association between exposure and outcome (D)</p> Signup and view all the answers

'What can be concluded if a series of hypothesis tests about the 'true' excess risk of TB in Basra indicate that hypothesized values between 1.1 and 1.5 are 'consistent with' the data?'

<p>'True' excess risk or possible benefit can be estimated within a specific range (D)</p> Signup and view all the answers

What does an association refer to in epidemiology?

<p>The likelihood that an association represents a causal relationship between exposure and outcome. (C)</p> Signup and view all the answers

What does the 95% confidence interval represent in epidemiological studies?

<p>The range of 'true' values that are 'consistent with' the observed data (C)</p> Signup and view all the answers

In epidemiological studies, what does random variation refer to?

<p>Chance fluctuations in the observed data (C)</p> Signup and view all the answers

What is the purpose of distinguishing between the 'true' or 'underlying' value and observed measurements in epidemiological studies?

<p>To understand the uncertainty associated with the measurements (C)</p> Signup and view all the answers

What is the relationship between parameters and statistics in epidemiological studies?

<p>Statistics estimate parameters (B)</p> Signup and view all the answers

What is used to calculate the Standardized Mortality Ratio (SMR) in epidemiological studies?

<p>$O/E$ (D)</p> Signup and view all the answers

What does an association refer to in epidemiology?

<p>The causal relationship between variables (B)</p> Signup and view all the answers

What is indicated if the relative risk (RR) is equal to 1?

<p>No association between exposure and outcome (D)</p> Signup and view all the answers

What does it mean if a hypothesis test reflects a lack of information due to few data available?

<p>The p-value will be high (C)</p> Signup and view all the answers

What does a p-value greater than 0.05 generally indicate?

<p>'True' values are likely to lie within the confidence interval (C)</p> Signup and view all the answers

What can be concluded if a series of hypothesis tests about the 'true' excess risk of TB in Basra indicate that hypothesized values between 1.1 and 1.5 are 'consistent with' the data?

<p>'True' values are consistent with the observed data (A)</p> Signup and view all the answers

What does a p-value greater than 0.05 generally indicate?

<p>Little or no evidence against the hypothesis (B)</p> Signup and view all the answers

What does it mean when a p-value is less than 0.05 in a hypothesis test?

<p>Indication of statistically significant evidence against the hypothesis (C)</p> Signup and view all the answers

What does an observed p-value of 0.0001 for IRR = 0.8 indicate in a power station example?

<p>Strong evidence against the hypothesis (D)</p> Signup and view all the answers

In epidemiological studies, what does random variation refer to?

<p>Fluctuations in observed values due to chance (C)</p> Signup and view all the answers

What is the purpose of defining a range within which the excess risk or possible benefit are likely to lie?

<p>Estimating where the 'true' value might lie (C)</p> Signup and view all the answers

What can be concluded if a series of hypothesis tests about the 'true' excess risk of TB in Basra indicate that hypothesized values between 1.1 and 1.5 are 'consistent with' the data?

<p>'True' excess risk probably lies between 1.1 and 1.5 (B)</p> Signup and view all the answers

What does an odds ratio estimate in a case-control study?

<p>'True' odds of being exposed to a particular risk factor (B)</p> Signup and view all the answers

What is indicated if the relative risk (RR) is equal to 1?

<p>'True' risk of developing a specific outcome (B)</p> Signup and view all the answers

What does it mean if a null hypothesis value lies within the 95% confidence interval?

<p>'True' value of epidemiological measures is exactly equal to the null hypothesis value (C)</p> Signup and view all the answers

How does statistical theory allow us to interpret the 'true' value of any measure used in this module?

<p>'True' value can be estimated within a certain range based on the observed value (D)</p> Signup and view all the answers

What does it mean if a p-value is less than 0.05 in a hypothesis test?

<p>Indication of statistically significant evidence against the hypothesis (C)</p> Signup and view all the answers

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