Stats Midterm

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shelbymailho
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111794
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Stats Midterm
Updated:
2011-10-24 15:35:48
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Statistics
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Midterm Review
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  1. Authority
    someone says it's true
  2. Rationalism
    use of reasoning to arrive at knowledge (syllogisms)
  3. Intuition
    Sudden insights
  4. Sample
    group of participants selected for study
  5. Population
    the targeted audience of your research
  6. Independent Variable
    • manipulated by the experimenter
    • -effect of alcohol on social behavior: IV=alcohol
    • -sleep deprivation on academic performance: IV=sleep deprivation
  7. Qualitative vs. Quantitative
    • Qualitative- involves the type of treatment
    • Quantitative- defined by the amount of a variable (dosage of drug)
  8. Quasi-Independent Variable
    Independent variables that are predetermined-making it impossible to randomly assign subjects
  9. Dependent Variable
    measured (measure of performance)
  10. Reliability vs. Validity
    • Reliability- consistency
    • Validity- are you testing what you say you're testing
  11. Descriptive vs. Inferential Statistics
    • Descriptive- analysis done for purpose of describing or characterizing data (mean, mode, SD, variance)
    • Inferential- using data for sample to make inferences or draw conclusions about the population
  12. Internal vs. External Validity
    • Internal- degree to which the researcher can infer that a relationship between the IV and DV is causal
    • External- addresses the question of generalizability
  13. Assumptions of Statistical Tests
    • 1. Normality (normal distribution)
    • 2. Homogeneity of Variances (variability between scores is roughly equivalent)
    • 3. Independence of Errors (how the test is administered)
  14. Nominal
    • qualitative variables, names
    • objects are measured by determining the category to which they belong
    • Can compare modes but no means or medians
    • -Social security number, sex of a child, religion of an individual
  15. Ordinal
    • Ranking, or magnitude (1st, 2nd, 3rd..)
    • No equal intervals or absolute zero
    • -Ratings of a task (easy, mildly difficult, difficult), marathon runners
  16. Interval
    • Magnitude and equal intervals between units, no absolute zero
    • -Celsius/Fahrenheit Scales
  17. Ratio
    • Magnitude, equal intervals, AND absolute zero
    • Allows for all types of numerical operations
    • -time required to complete a task, processing speed, length, weight
  18. Continuous vs. Discrete Variables
    • Continuous- infinite number of values between adjacent units on a scale (weight, height, processing speed)
    • Discrete-no possible values between adjacent units on a scale, it changes in fixed amounts (number of professors, cups of coffee)
  19. Random Sampling
    • Constant Probability
    • 1/N
  20. Case Control
    studies that begin after individuals have already developed or failed to develop the condition being investigated
  21. Cohort
    group of individuals who share a common experience
  22. Randomized Clinical Trial (RCT)
    • individuals assigned to study and control group
    • "chance" (randomization) is used to assign to groups
  23. Kurtosis
    peakedness of a distribution
  24. 3 Types of Kurtosis
    • 1. Mesokurtic (normal)
    • 2. Leptokurtic (peaked)
    • 3. Platykurtic (flattened)
  25. Variance
    • standard deviation squared
    • -the higher, the more dispersed the data is around the mean
    • SS/N
  26. Standard Deviation
    • how scores are dispersed around the mean
    • square root of SS/N
  27. Skewness
    • symmetricality of a distribution
    • can be positive or negative
  28. Z Scores
    • provides information about the location of scores in standard deviation units
    • provides: direction and magnitude
    • Mean= 0, SD=1
  29. Central Limit Theorem
    When the population distribution is not normal, the sampling distribution of the mean will be closer to the normal distribution than the population distribution
  30. Comparing one group of subjects to a population
    One Sample Hypothesis Testing
  31. If a score falls within the Critical Region:
    it is very unlikely to be just by chance
  32. Random Error
    • 95% of the population (in the middle of the distribution)
    • -if Z score falls within -1.96 and +1.96, it is not statistically significant
  33. Critical Regions
    • 5% of population outside of Random Error
    • 2.5% on each side
    • -if Z score falls in critical region, it is statistically significant
  34. Hypothesis Testing is
    ruling out chance
  35. Null Hypothesis assumes:
    • that there will be no statistical significance
    • Goal is to disprove/reject the Null
  36. Type I Error
    Saying something is significant when it's not (false positive)
  37. Type II Error
    Saying something isn't significant, when it is (fall negative)
  38. One-Tailed vs. Two-Tailed
    • One-Tailed: saying there is going to be a direction (this drug will increase attention)
    • Two-Tailed: saying it's going to be different (there is a difference in IQ between men and women)
  39. I Have A Crazy Teacher Dave stands for:
    • Hypothesis
    • Alpha Level (.05)
    • Critical Region
    • Test Statistic
    • Decision
  40. Independent/Between Measures t-Test
    • Two independent group- one dependent group
    • -Men vs. Women on time spent studying
    • -Exercise/Don't exercise on how many hours they sleep
    • -Study/Don't study on test scores
  41. Levene's Test
    • looks at if the variance between two groups is significantly different
    • If it is below .05, they are significantly different (violation of your assumption)
  42. A very difficult test will likely result in what type of skewed distribution?
    negative
  43. A sample's variability will be larger or smaller than the population from which it comes?
    Smaller
  44. The probability of Tye I Error is known as
    Alpha
  45. A Z Score has a mean of ____ and a standard deviation of _____.
    • mean=0
    • standard deviation=1
  46. If raw scores from a positively skewed distribution were transformed into z-scores, what shape would the standardized scores assume?
    Positive
  47. When one analyzes data based on a sample, one calculates a _____________.
    Statistic
  48. Mathematical methods used to draw tentative conclusions about a
    population based on sample data are referred to as _______ statistics.
    Inferential
  49. Which study can one most reasonably determine cause and effect?
    Experiment
  50. In Inferential Statistics, the object is to generalize from a _____________ to a ______________.
    • Sample
    • Population
  51. Which type of measurement: Sex of a Child
    Nominal
  52. Which type of measurement: Religion of an individual
    Nominal
  53. Which type of measurement: Time required to complete a task
    Ratio
  54. Which type of measurement: Ratings of a task (Easy, Mildly Difficult, Difficult)
    Ordinal
  55. In a normal curve, the mean will be ______________ the median and mode.
    Equal to
  56. In a normal distribution, approximately ________% of the scores fall
    from one standard deviation below to one standard deviation above the
    mean.
    68%
  57. The attitude of one group of employees differs from attitudes of the general population--what is the most appropriate hypothesis test?
    One-Sample t-Test
  58. If Levene's test is significant, the difference in means between the two groups _____________.
    Cannot be determined

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