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30 Cards in this Set
- Front
- Back
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31. Selection bias?
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a. Nonrandom assigment to study group
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32. Recall bias?
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a. Knowledge of presence of disorder alters recall by subjects.
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33. Sampling bias?
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a. Subjects are not representative to general population; therefore, results are not generalizable.
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34. Late-look bias?
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a. Information gathered at an inappropriate time.
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35. Procedure bias?
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a. Subjects in different groups are not treated the same.
b. E.g. more attention is paid to treatment group, stimulating greater compliance. |
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36. Ways to reduce bias?
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1. Blind studies (double blind is better)
2. Placebo responses 3. Crossover studies (each subject acts as own control) 4. Randomization |
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37. Normal~Gaussian~Bell-shaped curve?
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a. Mean=median=mode.
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38. Bimodal curve?
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a. 2 humps
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39. Positive skew?
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a. Mean>median>mode.
b. Asymmetry w/tail on right |
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40. Negative skew?
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a. Mean<median<mode
b. Asymmetry w/tail on left. |
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41. Null Hypothesis (H0)?
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a. Hypothesis of no difference (e.g., there is no association between the disease and the risk factor in the population)
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42. Alternative hypothesis (H1)?
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a. Hypothesis that there is some difference (e.g. there is some associated between the disease and the risk factor in the population).
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43. Type I error (α)?
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a. Stating that there IS an effect or difference when none exists (to mistakenly accept the experimental hypothesis and reject the null hypothesis).
b. P= probability of making a type I error. c. P is judged against α, a present level of significance (usually <0.05). |
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44. If p<0.05?
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a. then there is less than a 5% chance that the data will show something that is not really there.
b. α = you “saw” a difference that did not exist – e.g. convicting an innocent man. |
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45. Type II error (β)?
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a. Stating that there IS NOT an effect or difference when one exists (to fail to reject the null hypothesis when in fact H0 is false).
b. β is the probability of making a type II error. c. β = you did not “see” a difference that does exist-e.g., setting a guilty man free. |
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46. Power (1- β)?
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a. Probability of rejecting null hypothesis when it is in fact false, or the likelihood of finding a difference if one in fact exists. It depends on:
1. The total number of end points experienced by population. 2. Difference in compliance between treatment groups (differences in the mean values between groups). 3. Size of expected effect. b. If you increase sample size, you increase power. There is power in numbers. c. Power = 1- β. |
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47. 1, 2, 3, standard deviations?
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a. 1 standard deviation- 68% (34% each way).
b. 2 standard deviations- 95% c. 3 standard deviations 99.7% |
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48. Confidence interval?
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samples would be expected to fall.
b. CI = range from [mean-Z(SEM)] to [mean+Z(SEM)] c. The 95% confidence interval (corresponding to p=.05) is often used. |
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49. What does Z = for 95% CI?
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a. 1.96.
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50. Confidence interval note?
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a. If the 95% CI for a mean difference between 2 variables includes 0, then there is no significant difference and H0 is not rejected.
b. If the 95% CI for odds ratio or relative risk includes 1, H= is not rejected. |
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51. t-test vs. ANOVA vs. X2 (chi-squared)?
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-test checks the difference between the means of 2 groups. “Mr. T is mean”
b. ANOVA checks the difference between the means of 3 or more groups i. “ANOVA = ANalysis OF Variance of 3 or more variables. c. X2 checks differences between 2 or more percentages or proportions of categorical outcomes (not mean values). i. X2 = compare percentages (%) or proportions. |
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52. Correlation coefficient (r)?
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a. r is always between -1 and +1.
b. The closer the absolute value of r is to 1, the stronger the correlation between the two variables. c. Coefficient of determination = r2 (value that is usually reported). |
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53. Primary disease prevention?
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a. Prevent disease occurrence e.g. vaccination.
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54. Secondary disease prevention?
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a. Early detection of disease e.g. Pap smear
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55. Tertiary prevention?
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a. Reduce disability from disease e.g. exogenous insulin for diabetes.
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56. Disease prevention mnemonic?
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a. PDR. Prevent, Detect, Reduce disability.
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57. Mnemonic for reportable diseases?
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a. Hep Hep Hep Hooray, the SSSMMART Chick is GONE
b. Hep B, A, C. c. HIV d. Salmonella e. Shigella f. Syphilis g. Measles h. Mumps i. AIDS j. Rubella k. Tb l. Chickenpox m. Gonorrhea |
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58. Leading causes of death in infants?
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a. Skipped this section.
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59. Medicare part A?
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a. Hospital
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60. Medicare part B?
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a. Doctor bills.
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