DOI: 10.3886/icpsr06046.v1
title: Numerical Meanings of Probabilistic Expressions
title: Version 1

description: These data were collected to obtain a clearer understanding 
 of the quantitative meanings that people perceive in common words used 
 to describe probabilistic outcomes. For example, in everyday language, 
 people apply the expressions "always" and "certain" to events that 
 occur in fewer than 100 percent of their opportunities. In this study, 
 science writers were surveyed and asked to quantify, in a percentage 
 term, their understanding of each of 52 expressions. They were also 
 asked to indicate how they thought their readers would quantify each 
 term, giving both an upper and lower limit they thought their readers 
 would set for each expression. One group of expressions included the 
 word "probability", and ranged from "very high probability" to 
 "very low probability". Another used various forms of the word 
 "probable", such as "very probable" and "improbable". Other 
 expressions were centered around the word "chance": "better than 
 even chance" to "less than even chance". The survey also included 
 words like "always", "often", "frequently", "never", and 
 "sometimes". Also tested were expressions with regularly used 
 modifiers such as "very", or negation (not, un-, im-, in-), so that 
 the effect of such modifiers could be evaluated. The sample of 
 respondents was split to permit assessment of the effects of order of 
 presentation: half received a form that ranked the expressions within 
 15 groups from high probability to low, while the other half received a 
form ordering the expressions from low probability to high.
description: A total of 238 respondents from the population (37 percent 
response rate).
description: Datasets: 
DS0: Study-Level Files
DS1: Data ("Always"), Form A
DS2: Data ("Always"), Form B
DS3: Data ("Almost Always"), Form A
DS4: Data ("Almost Always"), Form B
DS5: Data ("Certain"), Form A
DS6: Data ("Certain"), Form B
DS7: Data ("Almost Certain"), Form A
DS8: Data ("Almost Certain"), Form B
DS9: Data ("Very Frequent"), Form A
DS10: Data ("Very Frequent"), Form B
DS11: Data ("Frequent"), Form A
DS12: Data ("Frequent"), Form B
DS13: Data ("Not Infrequent"), Form A
DS14: Data ("Not Infrequent"), Form B
DS15: Data ("Infrequent"), Form A
DS16: Data ("Infrequent"), Form B
DS17: Data ("Very Infrequent"), Form A
DS18: Data ("Very Infrequent"), Form B
DS19: Data ("Very High Probability"), Form A
DS20: Data ("Very High Probability"), Form B
DS21: Data ("High Probability"), Form A
DS22: Data ("High Probability"), Form B
DS23: Data ("Moderate Probability"), Form A
DS24: Data ("Moderate Probability"), Form B
DS25: Data ("Low Probability"), Form A
DS26: Data ("Low Probability"), Form B
DS27: Data ("Very Low Probability"), Form A
DS28: Data ("Very Low Probability"), Form B
DS29: Data ("Very Likely"), Form A
DS30: Data ("Very Likely"), Form B
DS31: Data ("Likely"), Form A
DS32: Data ("Likely"), Form B
DS33: Data ("Unlikely"), Form A
DS34: Data ("Unlikely"), Form B
DS35: Data ("Very Unlikely"), Form A
DS36: Data ("Very Unlikely"), Form B
DS37: Data ("Very Probable"), Form A
DS38: Data ("Very Probable"), Form B
DS39: Data ("Probable"), Form A
DS40: Data ("Probable"), Form B
DS41: Data ("Improbable"), Form A
DS42: Data ("Improbable"), Form B
DS43: Data ("Very Improbable"), Form A
DS44: Data ("Very Improbable"), Form B
DS45: Data ("Very Often"), Form A
DS46: Data ("Very Often"), Form B
DS47: Data ("Often"), Form A
DS48: Data ("Often"), Form B
DS49: Data ("More Often Than Not"), Form A
DS50: Data ("More Often Than Not"), Form B
DS51: Data ("As Often As Not"), Form A
DS52: Data ("As Often As Not"), Form B
DS53: Data ("Less Often Than Not"), Form A
DS54: Data ("Less Often Than Not"), Form B
DS55: Data ("Not Often"), Form A
DS56: Data ("Not Often"), Form B
DS57: Data ("Not Very Often"), Form A
DS58: Data ("Not Very Often"), Form B
DS59: Data ("Possible"), Form A
DS60: Data ("Possible"), Form B
DS61: Data ("Impossible"), Form A
DS62: Data ("Impossible"), Form B
DS63: Data ("High Chance"), Form A
DS64: Data ("High Chance"), Form B
DS65: Data ("Better Than Even Chance"), Form A
DS66: Data ("Better Than Even Chance"), Form B
DS67: Data ("Even Chance"), Form A
DS68: Data ("Even Chance"), Form B
DS69: Data ("Less Than Even Chance"), Form A
DS70: Data ("Less Than Even Chance"), Form B
DS71: Data ("Poor Chance"), Form A
DS72: Data ("Poor Chance"), Form B
DS73: Data ("Low Chance"), Form A
DS74: Data ("Low Chance"), Form B
DS75: Data ("Liable to Happen"), Form A
DS76: Data ("Liable to Happen"), Form B
DS77: Data ("Might Happen"), Form A
DS78: Data ("Might Happen"), Form B
DS79: Data ("Usually"), Form A
DS80: Data ("Usually"), Form B
DS81: Data ("Unusually"), Form A
DS82: Data ("Unusually"), Form B
DS83: Data ("Sometimes"), Form A
DS84: Data ("Sometimes"), Form B
DS85: Data ("Once in a While"), Form A
DS86: Data ("Once in a While"), Form B
DS87: Data ("Not Unreasonable"), Form A
DS88: Data ("Not Unreasonable"), Form B
DS89: Data ("Occasionally"), Form A
DS90: Data ("Occasionally"), Form B
DS91: Data ("Now and Then"), Form A
DS92: Data ("Now and Then"), Form B
DS93: Data ("Seldom"), Form A
DS94: Data ("Seldom"), Form B
DS95: Data ("Very Seldom"), Form A
DS96: Data ("Very Seldom"), Form B
DS97: Data ("Rarely"), Form A
DS98: Data ("Rarely"), Form B
DS99: Data ("Very Rarely"), Form A
DS100: Data ("Very Rarely"), Form A
DS101: Data ("Almost Never"), Form A
DS102: Data ("Almost Never"), Form B
DS103: Data ("Never"), Form A
DS104: Data ('Never'), Form B
description: The universe consisted of 637 members of the National 
Association of Science Writers in the United States and Canada.
description: The data are provided, as received from the producer, 
 in 104 discrete small files, each corresponding to one of the 52 
 probabilistic expressions and to one of the two survey forms. The files 
 have been edited by ICPSR for easier handling by statistical software. 
 Specifically, two lines of comment, which identified the expression to 
 which the file's data referred, have been removed from each file. In 
 their place, two variables have been added to each record: one 
 identifying the expression and a second identifying the form code. In 
 addition, the respondent identification code was edited to remove 
 blanks. Users should note that the data are not arranged in these files 
 in fixed columns but in a free-format list, with one record per line 
and each variable delimited by a comma.