### How Can I Calculate Standard Deviation (step-by-step) in R?

• Tessa

5 years ago

How can I calculate Standard Deviation, step-by-step, in R? Thanks! Do you know the formula for standard deviation? Can you elaborate on 'step by step'? Hi! Yes, I believe do! I'm trying to calculate sd for a specific data set. I am aware that I can simply use the sd function, but I need to calculate the standard deviation of a data set "by hand," using R. These are the values:  179 160 136 227 217 168 108 124 143 140 309 229 181 141 260 203 148 169 213 257 244  271 243 230 248 327 329 250 193 271 316 267 199 171 158 248 423 340 392 339 341 226  320 295 334 322 297 318 325 257 303 315 380 153 263 242 206 344 258 368 390 379 260  404 318 352 359 216 222 283 332 Thank you! $variance = \frac{sum((x-mean(x))^2)}{(length(x)-1)}$

• rightskewed Correct answer

5 years ago
> a <- c(179,160,136,227)
> sd(a)
 38.57892
> sqrt(sum((a-mean(a))^2/(length(a)-1)))
 38.57892


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