Sample Size

Determining Sample Size

The size of the population and the amount of error the researcher is willing to tolerate is what determines the size of the sample. The table that follows was developed for situations where the researcher wants to come within 5 percentage points (with 95 percent certainty) of what the results would have been if the entire population had been surveyed. A more flexible approach is to use a sample size calculator that allows you to enter your preferences.


Table for Determining the Needed Size of a Randomly Chosen Sample from a Given Finite Population

Population Sample | | Population Sample | | Population Sample
10 10 220 140 1200 291
15 14 230 144 1300 297
20 19 240 148 1400 302
25 24 250 152 1500 306
30 28 260 155 1600 310
35 32 270 159 1700 313
40 36 280 162 1800 317
45 40 290 165 1900 320
50 44 300 169 2000 322
55 48 320 175 2200 327
60 52 340 181 2400 331
65 56 360 186 2600 335
70 59 380 191 2800 338
75 63 400 196 3000 341
80 66 420 201 3500 346
85 70 440 205 4000 351
90 73 460 210 4500 354
95 76 480 214 5000 357
100 80 500 217 6000 361
110 86 550 226 7000 364
120 92 600 234 8000 367
130 97 650 242 9000 368
140 103 700 248 10 000 370
150 108 750 254 15 000 375
160 113 800 260 20 000 377
170 118 850 265 30 000 379
180 123 900 269 40 000 380
190 127 950 274 50 000 381
200 132 1000 278 75 000 382
210 136 1100 285 1 000 000 384
Population Sample | | Population Sample | | Population Sample

Krejcie, R. V., & Morgan, D. W. (1970). Determining sample size for research activities. Educational and Psychological Measurement, 30, 607-610.


Del Siegle, Ph.D.
Neag School of Education – University of Connecticut
del.siegle@uconn.edu

www.delsiegle.com