},{"id":"9097b3a0-2d91-4681-9f0d-5bbe16fb0f57","cardType":"basic","front":"Why are deviations squared when calculating variance?","back":"To stop positive and negative deviations cancelling.","points":2},{"id":"c74dc742-0792-4cca-9ed9-acd5c2a2aac1","cardType":"basic","front":"If heights are measured in cm, what units does variance have?","back":"cm².","points":1},{"id":"0d5d0dff-d5a1-4441-b32a-e1f9aca3224e","cardType":"basic","front":"Why is standard deviation easier to interpret than variance?","back":"It is in the original units.","points":2},{"id":"3ebd3a02-1a81-4535-91ea-6ac050e58476","cardType":"cloze","front":"The raw-data mean formula is [ ].","back":"The raw-data mean formula is $\\bar{x}=\\frac{\\sum x}{n}$.","points":null},{"id":"f5b44854-acc9-4530-82c0-8f86535190b5","cardType":"cloze","front":"Variance is the mean of squared deviations: [ ].","back":"Variance is the mean of squared deviations: $s^2=\\frac{\\sum (x-\\bar{x})^2}{n}$.","points":null},{"id":"795723db-f7a8-4c6f-ac77-0e358170436e","cardType":"cloze","front":"The efficient raw-data variance formula is [ ].","back":"The efficient raw-data variance formula is $s^2=\\frac{\\sum x^2}{n}-\\bar{x}^2$.","points":null},{"id":"5741f84c-b962-491b-aa17-5a2739ec8e91","cardType":"basic","front":"After calculating $\\frac{\\sum x^2}{n}-\\bar{x}^2$, what must you do to get $s$?","back":"Take the square root.","points":1},{"id":"7e0327f5-ceda-4ef1-958b-475f02c6c824","cardType":"basic","front":"For grouped data, which representative value is used for each class?","back":"The class midpoint.","points":1},{"id":"17a4e7cb-b72d-4712-bc2a-9fa5f5a4d363","cardType":"basic","front":"For the class $140145.","points":1},{"id":"37cc11c5-26a5-430b-8268-8c6323217875","cardType":"cloze","front":"For grouped data, the mean formula is [ ].","back":"For grouped data, the mean formula is $\\bar{x}=\\frac{\\sum fx}{\\sum f}$.","points":null},{"id":"cf779520-d719-4b69-a633-f330a1e20f17","cardType":"cloze","front":"For grouped data, the variance formula is [ ].","back":"For grouped data, the variance formula is $s^2=\\frac{\\sum fx^2}{\\sum f}-\\bar{x}^2$.","points":null},{"id":"1be27a44-b198-4c15-8ec6-0cf04918acb7","cardType":"basic","front":"Why is standard deviation from grouped data only an estimate?","back":"The original values are unknown, so midpoints are used.","points":2},{"id":"e297649e-97c2-47c9-a068-3205b4fed806","cardType":"basic","front":"If distances are recorded as 10-19 miles to the nearest unit, what midpoint is used?","back":"14.5.","points":1},{"id":"8e53aeba-23d0-415f-81e6-504144d87b28","cardType":"basic","front":"Rearrange $x=\\frac{t-12}{3}$ to make $t$ the subject.","back":"$t=3x+12$.","points":1},{"id":"c4196278-9e28-4c32-8cd3-dea4d2c7d0de","cardType":"cloze","front":"If $T=a+bX$, the mean and median are transformed using the [ ].","back":"If $T=a+bX$, the mean and median are transformed using the same formula.","points":null},{"id":"36e12580-24a8-4d1e-bd68-c4def24abb63","cardType":"basic","front":"If $T=a+bX$, by what factor is the standard deviation multiplied?","back":"$|b|$.","points":1},{"id":"dc32ca26-d8cf-43c9-b2b6-ca160226fe8d","cardType":"basic","front":"If $T=a+bX$, by what factor is the variance multiplied?","back":"$b^2$.","points":1},{"id":"a86588f8-7b99-4e77-a47c-2948543e3162","cardType":"basic","front":"Why d

Variance and Standard Deviation Flashcards

Variance and Standard Deviation Flashcards

Variance and Standard Deviation Flashcards

Variance and Standard Deviation Flashcards