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PDAM #2
| Question | Answer |
|---|---|
| What is reliability of data (2) | 1, consistency > the data are repeatedly similiar 2, random error is zero |
| What is validity of data | accuracy > are you measuring a the right thing |
| What are dimesions of reliability and valibility on darf target (4) | 1, reliable+valid = correct & consistent (+- all near middle) 2, reliable+not valid = consistent but not in the middle but somewhere else 3,unrealible+valid = on average in middle but distibute overall 4, unreliable+not valid = upperall all e.g. |
| What is formula for measurement theory (2) | 1, Observed score(O) = True score(T) + Error (E) 2, E= systematic error (S) & Unsystematic error (R) |
| What is systematic error (3) | 1, a consistent deviatior from the true value > shifts result always in the same direction 2, it is biased (like people underreport their income, scale is +5kg always) 3, can be reduced with better question wording, control group etc |
| What is unsystematic error (3) | 1, also called random error 2, unpredictable fluctuations around the true value 3, it cancels out on average |
| What are 4 central tendencies for a data set | 1, mode 2, median 3,percentiles 4,mean |
| What is the mode (3) | 1, the most frequently occuring value(s) for a variable 2, advantages - suitable for nominal and ordinal values without exterme value 3,disadvantages - no information about differences between values |
| What is the median (3) | 1, the value in exactly in the middle of ordered dataset 2,advantages - is resistant to extreme values 3,disadvantages - doesn´t capture variability in datasets |
| What are the percentiles (2) | 1, tell why relative number of observation lies under this observation 2, important is 1.quartile (25th percentile) , 2.quartile (median) and 3.quartile (75th percentile) |
| What is the mean (3) | 1, arithmetic average of all the values 2, advantages - gives more informaton about the central location and is more stable 3,disadvantages - sensitive to outliers |
| What are outliers | we can flag them, but there is not "one-fit-all" definition |
| What is range (3) | 1, the difference between the smallest and the largest value (range = max value - min value) 2, advantages - gives information about the spread 3,disadvantages - sensitive to extreme values and unstable across different samples |
| What is deviance (2) | 1, deviance = x- x̅ 2, total deviance (sum of all deviances in a data set) is always zero |
| What is Sum of Square Errors (2) | 1, Sum od square errors= ∑ (x-x̅)² 2, not comparable across groups/samples because it gets bigger as n increases |
| What is variance (2) | 1, s² = ∑ (x-x̅)² / (N-1) or Sum of square errors/(N-1) 2, also called Mean Squared Error |
| What is Standart deviation | s= √ (∑(x-x̅)² / (N-1) ) |
| What do Sum of Squares, Variance, and Standart Deviation reflect (4) | 1, The variability in the data 2, How well the mean represents the observed data 3, Error 4, Homogenity (similarlity) or Heterogenity of rating |
| What is important to when reading summary statistics (2) | 1, can be easily manupulated, it is important to think critically about it 2,summary statisticsd can completely hide the real structure of data |
Created by:
semester1.IBWL