I can’t compute those statistics without the data — please provide the list of sibling counts or a frequency table/histogram.
Explanation / What I need
- To compute mean, median, sample standard deviation, Q1, Q3, and the requested percentiles I need either:
- the full list of each respondent’s number of siblings (e.g., 2,0,1,3,…) OR
- a frequency table (e.g., 0 siblings: 10 respondents; 1 sibling: 20 respondents; …) OR
- a clear image of the histogram with bin counts.
- Also tell me the sample size if it’s not obvious.
How I will compute each item (so you know what I’ll do once you send the data)
- Mean:
- Formula: $\bar{x}=\dfrac{1}{n}\sum_{i=1}^n x_i$
- Steps: sum all sibling counts, divide by $n$.
- Median:
- Sort the data. If $n$ is odd, median is the middle value. If $n$ is even, median is the average of the two middle values.
- Sample standard deviation:
- Formula: $s=\sqrt{\dfrac{1}{n-1}\sum_{i=1}^n (x_i-\bar{x})^2}$
- Steps: compute deviations from the mean, square them, sum, divide by $n-1$, take square root.
- First quartile (Q1) and third quartile (Q3):
- Method: sort the data. Q1 is the median of the lower half, Q3 is the median of the upper half. (Note: there are multiple conventions — I can use the Tukey method or the $ (n+1)p$ interpolation method; tell me if you need a specific convention.)
- Percent with at least 3 siblings:
- Compute count of respondents with $x\ge 3$, then percent$=100\times\frac{\#\{x\ge3\}}{n}$.
- “85% of all respondents have fewer than how many siblings?” (85th percentile)
- Find the 85th percentile (value $x$ such that 85% of observations are less than $x$). Methods:
- For discrete counts with a frequency table, find the smallest sibling count for which the cumulative percent is $\ge85\%$.
- For interpolation (continuous-style), use the position $p=(0.85)(n+1)$ and interpolate between sorted values.
If you paste the raw data or a frequency table here, I will compute each statistic step-by-step and give the numeric answers.